How does a fiberglass newbie use less epoxy?

[Garnett]

It seems taken as a given that everyone new to working with fibreglass will use more epoxy and be left with a weaker structure than the pros.

Is there no hope for newbs? Or are there ways we can minimise the inefficiency from the get-go?

[Ian McColgin]

Yeah. Read the GoogeBros book and follow the directions.

I put on a thin layer of epoxy and stick the glass to that when it's tacky enough to hold the glass more or less, then add epoxy spreading with a plastic blade and roller to press it in so I get full wet-out but leave the warp and woof of the glass a little proud. That way I don't have the glass floating up to the epoxy surface. The weave can be filled in later with modestly thickened epoxy if you like but again aggressivly spread to make it as thin as consistent with filling the weave.

G'luck

[Canoeyawl]

Lucky Luke has a lot to say about it... you might check out his thread
Good advice to read the book.

[ILikeRust]

You might do well to ask your question over at the Plastic Classic forum. Fiberglass vs. wood, and all that, you know, old chap.

[Garnett]

Thanks for the pointers guys - some good starting points.

[JimConlin]

Plastic squeegees are a good way to get resin pushed around while controlling thickness.

Adding peel ply over your laminate allows squeegeeing it harder and it leaves a blush-free textured ready-to-bond surface as a bonus. It allows filling cloth weave in one coating.

If you're really serious about high ratio composites, there's vacuum bagging. It takes a little investment in tools and some planning, but it's not rocket surgery. There's a good how-to booklet/manual from West System.

[jerry bark]

I simply wet out my glass and then roll it with a foam roller until its "dry." if the cloth looks wet or has a sheen on it take your roller over it some more. if I get it just right it does not have a wet surface appearance.

The folks at Aero-marine told me that the ideal is 1 oz of epoxy for each 1 oz of glass but that home builders can rarely do that well and to strive for 1.5 oz to 1 oz. I checked my method and find that i was getting slightly less than 1.5 oz to 1 oz so I call it good.

Jerry

[Garnett]

Thanks. Both those methods sound effective. I think vacuum bagging might be a step too far, but I was thinking about a poor man's peel ply.

Jerry, I'm sure some answers will be apparent as soon as I get started, but do you brush the epoxy on to dry glass held in place by tape and then roll it? How wet do you get it? When rolling, do you get to the point where your roller drips epoxy you're taking off the glass?

[Ian McColgin]

My experience is exclusivly putting glass over wood so I want it to stick.

I never use foam rollers to move the epoxy onto a surface. Even disposable brushes I use sparingly, more in glue settings than covering or glassing.

I pour and plastic spatula spread as thin a coat as I can. It's amazing how far you can spread the goo once you get vigorous with the plastic blade. When that's just ready to go off, I lay the glass on. This helps keep the glass from bunching or moving too much during the first wet-out. It often helps to either tape or staple judiciously. If you staple, have a roll of some moderatly stiff plastic to staple right through, protecting the stapler from glue and making later removal of the stable easier.

Once the glass is in place, I then pour some epoxy at a convenient place near the center of the work and start really press-spreading it. Here I might also use a roller, but not foam. Sometimes I have a nice hard rubber roller at hand. Other times I use a baker's rolling pin. Bot protected by plastic wrap so's clean-up is easy. But mostly I spread by plastic spreader.

The big advantage here, besides using less epoxy and keeping the glass from floating away from the wood, is NO BUBBLES TO CHASE. Wetting-out from the top really ensures that you don't trap air in the glass under epoxy, air that can be a real pain to squeegee out and usually results in shifting the glass on the surface, making more bubbles.

As mentioned earlier, I spread this layer thinly enough that while the glass is fully wetted - transluscent with no white left - the weave of the glass is a bit raised. Once the epoxy has gone off enough that the glass will stay put, you can hot coat a smoothing layer of epoxy, but I preferr to wait a day or so, light sand except where some fairing is needed, vacuum and then tack with acetone, and then put down a truely fair finish layer of epoxy.

As you practice with the plastic blade, moving the epoxy puddle is a bit like progressive snow-ploughing as you move the wave off goo along. The outside and trailing edge of your blade, where the epoxy is rolling off onto new territory, is pressed a bit harder than the inside leading edge, so you're moving as much goo as possible but not leaving a line of goo off that inside leading corner of the blade.

[Garnett]

Wow! Thanks a lot Ian. That makes a lot of sense. The only part I have trouble visualising is:

"Once the epoxy has gone off enough that the glass will stay put, you can hot coat a smoothing layer of epoxy, but I preferr to wait a day or so, light sand except where some fairing is needed, vacuum and then tack with acetone, and then put down a truely fair finish layer of epoxy."

How do you "hot coat a smoothing layer of epoxy" and how would you change your methods if you did not have access to the equipment to vacuum?

[peterchech]

What about this question of "poor man's peel ply"? Can a thick plastic dropcloth be used, thereby saving weight (no filler coat of epoxy) and sanding?

[JimConlin]

I prefer to apply the cloth dry and then wet through it. The practice of applying resin to the substrate before applying the glass makes it hard to get the glass down straight. Letting the resin begin to cure has some other risks, too. If here's any unevenness in the resin film thickness or temperature, the resin will kick off unevenly and some of it could be too viscous to wet the cloth or push through it. You don't want puddles of resin under the glass. Peel ply is cheap- about $.16/ft^2. Nylon taffeta from the yard goods store is OK and sometimes cheaper still. Laying peelply over the glass and squeegeeing it leaves a flat surface with the weave filled, in one go. No worries about secondary bonding. While polyfilm is cheaper still (maybe $.06/ft^2) and is good for herding bubbles, it needs lots of sanding to be bondable or paintable and I've found it doesn't lie down as flat as peelply.
Cleaning a glossy layup with acetone is unnecessarily toxic , expensive and ineffective. Soapy water and a scotchbrite do the job nicely.

[Garnett]

This is turning out to be a really instructive thread for me.

Jim, I did wonder about different layers of epoxy all at different stages of curing, but I'm completely new to all of this.

I can get peel ply over here for the equivalent of $0.32/ft^2 and so looking at the Bill of Materials for the boat I intend to build I'd need to spend about $80 to get the same amount of pel ply as the amount of fibreglassed specified.

Not a great deal if it greatly improves my chances of a) making a stronger boat, b) making a saving on amounts of epoxy used, and c) saves considerable time.

On e other newbie question: what's a "glossy layup"?

[JimConlin]

This is turning out to be a really instructive thread for me.

Jim, I did wonder about different layers of epoxy all at different stages of curing, but I'm completely new to all of this.

I can get peel ply over here for the equivalent of $0.32/ft^2 and so looking at the Bill of Materials for the boat I intend to build I'd need to spend about $80 to get the same amount of pel ply as the amount of fibreglassed specified.

Not a great deal if it greatly improves my chances of a) making a stronger boat, b) making a saving on amounts of epoxy used, and c) saves considerable time.

On e other newbie question: what's a "glossy layup"?

A European source for peelply is https://www.airtechonline.com/Airtec...5&ProductID=12 44.00 € for 25yds (125 ft^2).

A glossy layup is epoxy that has cured without peelply on it. Its texture will be glossy. Depending on the type of epoxy and on curing conditions, It might have (the dreaded) amine blush which needs to be washed off. In any case, It needs sanding before painting or subsequent bonding. Peelply leaves a texture that is without blush and needs very little prep before the next coating or bonding.

[Todd Bradshaw]

I think the key to using less epoxy is to work with smaller batches and to have someone available to mix a continuous supply of them as needed. That way you waste less in terms of leftovers and the resin is freshly-mixed and not in some state of starting to stiffen (as it stiffens, you use more of it and it saturates cloth more slowly). Other than for tipping out the surface on filler coats, I have no use at all for brushes when applying epoxy. They are about the poorest way possible to try to control application thickness, which is what being resin-stingy and generating a strong, fiber-rich layup is all about.

Before you start messing with vacuum-bagging, peel-ply, or Ian's rather bizzare method above (which to my mind has "formula for disaster for a beginner" written all over it) you need to learn to lay cloth down, saturate it with a roller or squeegee, get it down tight and leave it with a thin layer of resin in and on it and with the cloth weave showing very neatly and uniformly all over the surface. This is "Basic Fiberglassing 101" and you learn it by doing it and build your skills and confidence as you go. It is the basis for all fiberglass hand layup. For sheathed wooden boats, the cloth layer is later filled with plain resin to hide the cloth texture and sanded smooth. For all-composite layups, various other layers are then applied the same way, on top of the first layer.

Cloth tends to move and change shape as you saturate it and stick it down, so ideas like stapleing or taping it down in position ahead of time are quite often more hassle than help. Personally, I think you are better off just draping dry cloth neatly over the hull, starting your saturation using a roller or squeegee either in the middle and working out in all directions, or at one end and moving toward the other end. Spread the batch of resin quickly over an area so that it can start saturating the cloth. Then immediately go back in where you first started and work it down smooth, wrinkle and bubble-free, tight on the wood with a uniform cloth texture on its surface. About the time you have finished this area of a few square feet, your assistant should have the next batch of resin freshly-mixed and ready to go - so that you can proceed to move to the neighboring area without any sort of delay - and with fresh, un-jelled resin.

Personal preferences - everybody has their own and your mileage may vary as you get experience, but these are mine for fiberglass layup:

Rollers - I use the yellow Gougeon foam rollers, full length or cut down on the band saw if I need short ones. They have a fine texture and don't eat up (and waste) too much expensive epoxy.

Squeegees - I make my own from a scrap block of ethafoam packing foam, cutting slabs 3/8"-1/2" thick by maybe 4"x6" with a bread knife. I much prefer them to the typical plastic squeegee and nothing I've seen yet will "comb" the saturated surface of a layer of cloth out so uniformly. I learned about them back in the early 1970s from a couple guys at the old Moore-Vega canoe factory and have never found anything better (or cheaper).

Cloth - I drape the cloth over the hull (dry) and then walk along with a pair of sissors and trim the factory-woven selvedge edge off. In order for a flat, squarely-woven piece of cloth to eventually conform to a curved shape, the weave is going to need to move on itself a little bit. Removing the tight factory edge allows this to happen a bit more easily. Wear gloves whenever you handle the cloth, because the sizing that helps it take resin doesn't like moisture or oil from your fingers and they can make spots that don't saturate well.

Solvents: None...period. Other than a water wash in cases of removing amine blush or prior to sanding, the only foreign chemical or substance that I apply to my epoxy surfaces is the final paint or varnish. With proper work, chemicals simply are not needed and can sometimes cause problems that are quite hard to fix.

Peel-Ply - I'm in the fabric business. Those who scour the fabric stores for poor-man's Peel-Ply (cheap, light nylon or polyester that will do the job) should be aware that most of these are not "raw" fabrics. They have often been treated with various substances (fluorocarbons, silicones, sizings, etc.) to give them certain characteristics (water repellency, better UV life, more body, etc.) and make them more suitable for their original intended use (which ain't as Peel-Ply). It's certainly possible that using them on your boat and in contact with fresh epoxy might lay down a thin film of some sort of unwanted chemical. Nobody wants a thin film of silicone between the layers of their lamination, so choose wisely and if you find one that works, stick with it. Don't expect the folks at the store to know what might or might not be on it (they're usually pretty clueless) and don't expect it to say anything helpful on the end of the bolt other than just the basic fiber composition (and most likely "Made in China"). In any case, learn to do a decent hand layup first as it is the cornerstone of all fiberglass work. You can mess with Peel-Ply and other exotic techniques later.

[Garnett]

A glossy layup['s] texture will be glossy... It needs sanding before painting or subsequent bonding. Peelply leaves a texture that ...needs very little prep before the next coating or bonding.

Ahhhhh. Another penny drops.

Todd - thanks a lot for that long post. It makes a lot of sense. I think Ian's method is very similar to the method described by Lucky Luke and it does make sense also, but I agree that someone like me could mess it up royally!

I'm slightly daunted by the idea of draping fiberglass over the boat dry without anything holding it down. I worry about a flat sheet over a curved surface. Presumably, after you've taped the ply sheet seams with fibreglass tape you can put the glass fabric down on each ply sheet individually, to follow any curve in the wood.

[Ian McColgin]

I suspect that differences between what I was trying to write and Todd's more careful explanation are not so very large. I don't have the gear or knowledge for vacuum bagging and I have not glassed anything past verticle except once under a rock-gash in a lead poured into glass. But mostly I turn the work such that the place I'm working is pretty nearly horizontal and thus, like Todd, find little reason to tape or staple.

It sounds like Todd may apply the glass on a dry piece. If so, there we differ. I like to put it down on something with a skin of epoxy on it and then wait as it goes off till the glass is not positivly lubricated by the epoxy. I happen to like the flat plastic spreaders but hard and I think even thin foam rollers not only do the job but are likely to move the glass around less, and so might be better in most hands. It's just when I started in the mid '60s helping my dad (with polyester resin) glass our old Knockabout it was easiest to make plastic spreaders and so I learned that way.

Doing a little at a time really helps, not just small batches of epoxy at a time but also not too large a sheet of glass or too many that join.

I do think having the epoxy worked hard enough that the glass is saturated but weave still proud is good. The GoogeBros have some nifty ways to cut while tacky and join bits of glass whether seperate panels or needed darts to get the flat fabric to conform to the round hull but I could never use them very well. I just lap the pieces, making the lap as narrow as I can. When all is cured (weave still proud) I fair it with a grinder and as needed fair dips or ripples with thickened epoxy before I sand and tack all to put on the final weave-dimple filling coat.

I only 'hot coat' the final coat if there is only one piece of glass and no glass to glass joints to be cleaned off. I am not one to advise on hot coating since I just don't do it enough to think I really know the limits. Mine have worked but that could be more luck than science.

Get the WEST book for more thoughts.

G'luck

[RodB]

Garnett, Todd Bradshaw told you as clear as possible how to do it right and avoid problems. Todd always offers clear concise and straight information. Follow his adivce and you will not be sorry. There are some ideas recommended here that will certainly not make your tasks ahead easier.???

Your comment on the cloth not staying on the curved hull... its just common sense that you can tape the edges on each side of the hull so that it will stay in place more or less, but as you began to squeege the epoxy (as dry as possible in the initial wet out step) the fabric will move some in the direction you are pushing the epoxy. Its really not difficult at all if you just dive in and get the "feel" of it. Todd told you precisely how to do it... follow his advice. If you perform a good "wet out" step with a squeege (dry fitted cloth on bare wood) and then proceed to fill the weave in succeeding applications... ending up with enough epoxy covering the fabric so that you can sand to a nice satin finish (80 grit)and still leave the fabric buried, you will fine it difficult to do the job any better. I'd bet it difficult to tell much practical real world difference in slightly adjusting the amount of epoxy per cured plywood glassed panel up or down. I just glassed last night mostly along the line of Todds recommendatons... I have not found a better approach in several years... Look at the end of page 5 to see what I mean.

http://forum.woodenboat.com/showthre...d-glueup/page5

Heres a first coat wet out of 6 oz cloth with a squeege..... see how "dry" the application looks, but the fabric is saturated with epoxy and sitting right down on the wood as it should.




RodB

[Garnett]

Thanks Rod. I'm sure you're right about diving in. I've seen it said a lot. But I've also seen a lot of comments along the lines of "newbies use twice as much epoxy and make a heavy weaker boat".

I'm just trying to see if I can improve my chances of doing a good job first go!

[RodB]

Glassing with minimal epoxy is about controlling the amount of epoxy you lay down as you glass.

Todd told you the best approach... if done properly, you will end up (after sanding) with the fabric right next to the wood, buried in epoxy... but not too much... and its hard to do better than that when it all comes out in the end.

Look at the section on glassing the panels with "pre bend" near the end of the first page of the thread I gave you above.... Heres the link to page one. I covered epoxy application for max control in detail.... with a 3.5" roller and using a small platten as a roller pan.... see pics.

http://forum.woodenboat.com/showthre...ing-and-glueup

Rodb

[jerry bark]

Todd gave you some nice directions and I am sure his approach will work great. I generally work alone so this is what I do that works for me:

I use the cheapie foam rollers from JEN for about a buck each I cut them into half and use a suitable roller frame. then I mix up about 300 grams of epoxy (i use a scale to measure rather than pumps, 300 grams is about 10 ounces) if I have a smaller piece I mix less. them i roll out a coat to just wet the wood, i roll until the roller is leaving a trail of foamy epoxy behind. the foaming is caused by the roller pulling the last bit of epoxy from the surface. once you do this you will know what i mean.

I pour my epoxy right into a roller tray and work out of that.

then i roll out my glass carefully working with a gloved hand to get it to lay as smoothly as is reasonable, it will start to wet itself out here and there which helps keep it in place.

then use the roller to apply more epoxy just like you would painting a wall, except that i work to slowly wet out the cloth. I want just enough epoxy that the cloth becomes close to clear. I then move along and come back to re-roll with a mostly dry roller.

when you have the epoxy wetted so that its clear, but rolled dry enough that the weave of the fabric shows at the surface you have it. it should look like fabric, not like the surface of a lake on a glassy calm morning. if you do not have a fabric texture on the surface go over that part with the roller again and roll firmly to pick up some of the epoxy and move the epoxy to somewhere else.

roll, roll, roll.

I then let my epoxy set up overnight and give another very light coat or two until the fabric texture is filled in.

this photo shows how I want it to look:



don't forget to:

roll, roll, roll your glass, firmly on the hull.

as for using "twice the epoxy to make a heavier, weaker hull" I would not worry about that unless you are building a very light boat; the extra few pounds of epoxy won't matter. as to strength, well i have not seen any research on the relative strengths of various layups but I doubt the difference matters in most home built boats.

cheers
jerry

[Garnett]

Great info, thanks guys. I think I've got a much better idea of what's involved.

Todd, just read your build thread all the way through - fantastic looking project, and a great resource for other amateurs - very generous of you to put so much time into documenting it so thoroughly.

Is there any problem with coating the glass with several thin layers over time, as described? Will the different layers bond to each other ok?

[boattruck]

Garnett, If we are glassing plywood with cloth, as I'm guessing you are, we tailor our glass and lay it out, if it is vertical or more you will need tape to hold it temporarily. I wet out through the cloth with a squeegie or brush and roller if it is uphill. work the cloth from the center to the edges( remember that the wood will keep sucking up resin for a while...), mostly 'on the bias' or 45%, till you have a nice matte looking smooth finish, there is no advantage in my opinion, to trying to fill the weave, this much extra resin lets the cloth 'float' around, and coming back and adding it never made any sense at all to me...If this is to be paint grade, I like to get my fairing on while the resin is still 'green', so that when we do our first sanding/ fairing we are not removing any of the cloth we just bought...or messing with blush...As others have outlined above, practice, practice will also help a lot...Cheers, BT

[Garnett]

Thanks BT. That's interesting.

I've got a couple of questions:

Does using the squeegie ever shift the glass fabric from its intended position on the hull? I think I'd be worried of pushing too hard and pulling the cloth away from where it should be.

I thought you needed to fill the weave of the glass so that when you then sand/fair (what's the difference?!) the hull you're never taking off glass, just proud resin.

It sounds like instead of filling the weave with epoxy, you use more fairing compound. Is that right? I wasn't aware you could do that. How much epoxy and fairing compound would you use for a boat that needed say 20m^2 (24 sq yards) of glass fabric?

[Todd Bradshaw]

Yes, a squeegee (or a roller) can and will move the glass (or distort the weave pattern, parallelogramming it). This can be both a plus and a minus. It can tend to pull glass away from an area or off the surface (a minus, usually caused by applying too much pressure) or be used by the builder to push glass into an area. This is something you experience when glassing inside of a hollow (like the inside of a canoe or an inside seam on a stitch-and-glue boat). It's not uncommon as you saturate the fiberglass inside of a hollow shape to find that your actions of starting down in the bottom and squeegeeing or rolling upward toward the sheer are tending to pull the cloth away from the surface, making big bubbles in your laminate. The fix for this is to go back in and squeegee or roll the other direction - down into the middle in those areas. The tension the squeegee is putting on the cloth is what is moving it and pulling it away from the wood, so applying some strokes in the opposite direction moves cloth back into that area, easing the tension and allowing the cloth to lie back down on the wood. It sounds a lot more complicated than it really is, but any time you can't seem to keep the cloth down on the surface the fix is usually to move a bit more fabric into that area and ease the tension on it. Again, this is something you learn by doing and the first step is to have a pretty critical eye as you work. Something that can be fixed with a couple light swipes with a squeegee while the resin is still "wet" can be a royal pain in the rear to fix after the stuff sets up.

If using a typical plastic squeegee, it's not a bad idea to round the corners of the blade a bit as sharp corners sometimes tend to snag yarns of the cloth and move things you didn't want moved. That's another thing I like about the foam squeegee - no sharp corners. Also keep in mind that aggressive rolling or squeegee work (moving too fast or pressing too hard) tends to trap air bubbles down inside the cloth. They're generally small enough that they aren't structural, but in the case of a clear finish, they do show and aren't pretty to look at. With practice, you learn a balance between pressing hard enough to get a thin lamination, free of excess resin, and over-doing it on the pressure and filling your cloth with bubbles in the process.

The best stuff to use to fill the weave and fair the surface (straight resin or a fairing compound) depends on the application. Fairing compounds (resin/microballoon mixes) are certainly faster and easier as the job can be done in one or two passes and they are made to sand easily once hardened. A straight resin application may take as many as five or six coats, rolled on, to do the job. My rule of thumb there is to roll coats on until the weave is totally gone and then add one more as a bit of a cushion, allowing you to sand it smooth without cutting the cloth. Coats are rolled on just as soon as the previous coat is stiff enough that you aren't disturbing it. It can take some time, but nearly all of it is spent drinking beer while watching epoxy harden and the actual rolling part just takes a few minutes.

On beach-able small boats and paddle-craft (whether clear-finished or painted) I always fill with plain resin. Fairing compounds are designed to sand easily - but sanding is a form of abrasion. Beach rocks and river rocks are also a form of abrasion, just with a much coarser grit. A straight resin filler layer is at least two to three times more abrasion resistant than one made from fairing compound. It will protect the load-bearing glass skins better if the boat will encounter rocks. On the other hand, if the typical use for the boat is not one where it may encounter rocks, fairing compound will do just fine.

A lot of folks don't bother to do so, but if you want the best possible paint job over a fairing compound containing microballoons (which most do) you should apply the compound, fair it out by sanding and then give it one more top-coat of plain resin and a quick final sanding before painting. The reason is that the balloons are hollow. When you sand them, some of them at the surface will get cut open, leaving little bitty air-filled craters on the surface. These don't usually fill with paint. They can sometimes leave little pits in your paint job - or - the paint may bridge the gaps, trapping the air in there. Later on, the hull may heat up in the sun, expand that air and pop the paint bridging the craters, leaving similar pits. A resin top coat won't fill in the craters either, but it's strong enough to bridge them with a covering that isn't likely to pop later. It's all a matter of just how picky you want to be about your painting job, but it's worth knowing about.

There have been a couple mentions of laying cloth into wet or tacky resin and then saturating it with more. While certainly a good way to get the cloth down tight and keep it from moving around on you, I think you have to look at the individual task to decide if it's more desirable than starting with dry cloth on a dry hull. For small, irregular shapes, it's dynamite. We used to make helmets that way and being able to "pre-stick" a flat piece of cloth neatly and wrinkle-free to a sphere-shaped mold was very helpful. On a big object like a hull though, it's more problematic because of the time factor. If you wait for the pre-coat to achieve the proper tacky state, are you going to be able to get the whole hunk of fiberglass down before the resin moves on in its cure cycle to a not-so-proper state? There is a certain unpredictability there that can be a really serious problem if you can't get the job done in the available amount of time. It's also possible for cloth to absorb a small amount of resin as you put it down and if that resin happens to harden before you get there with the saturation coat, you're screwed. It will be stiff, white, resin-starved and will probably never absorb enough additional resin to properly saturate and turn clear. Obviously, this time frame will depend on the particular resin you choose, its pot-life and the weather conditions, but it's another reason that I prefer the dry method. No fiberglass area gets any resin on it until you are ready to work on that specific area. This allows me to use fast hardener for just about everything, which saves time. I'll fiberglass a 15'-20' boat - cloth, extra reinforcement and half a dozen filler coats, all done in one long day. Let it cure for 4-7 days (so that you aren't making dust from green epoxy, which is a health hazard) and sand it smooth, ready for paint or varnish.

[Garnett]

Todd, I'm so grateful for the time you've taken to explain all this. You and the other posters in this thread have been really patient and I feel pretty confident now about the aspect of the build that was causing me the most concern.

That last post really fills in the gaps I had.

[CundysHarbor]

To me, the reality of epoxy/glass work is that by the time I finish the project, I have it down pat. Next time, years later, I go through the whole learning process again.

[peterchech]

Todd your posts are extremely helpful as usual.

I usually pre-coat the wood before draping the cloth. But only because the epoxies I have used have been fairly thick and gave trouble penetrating, and the individual hull sections I have done have been relatively small. When I was working with West System epoxy it penetrated nicely from the outside, though it broke the bank :-)

Does anyone have experience draping plastic sheets onto the hull over the epoxy and glass, and rolling it down like peel ply? It would still require sanding but perhaps would save that second or third filling coat, and the sanding associated with that?

[Todd Bradshaw]

I can't remember who it was, but there was somebody on the forum a while back who was building flat-paneled boats (hard chine ply, I presume) and covering their wet epoxy with some sort of stiff, mylar-type stuff. When they later peeled the plastic off, the surface was amazingly smooth. Obviously, this would be very hard to do on a rounded shape, but it certainly worked nicely on flat panels. I haven't tried it on large areas, but for small repairs and gelcoat patching on polyester fiberglass boats it can be done with Handi-Wrap. The surface of polyester has to be sealed off from air in order to harden tack-free, so the main objective for the technique is more as a sealer than a smoother, but it did smooth things out to some extent.

The problem with the idea as I see it for typical epoxy work is that in order to generate that smooth, texture-free surface, there would need to be more resin applied than is needed to properly saturate the cloth. If you don't use something like a vacuum or the stiffness of the plastic to keep some pressure on the surface, your cloth may end up floating in a thick-ish blanket of resin, rather than being down tight on the surface. Good Peel-Ply is just porous enough that you can actually squish some of the excess resin through it and remove it from the lamination as you squeegee it down tight. It will still have some cloth weave texture, but it will be the very fine weave of the Peel-Ply yarns, not the much coarser glass cloth texture. Trying to do the same with plastic sheeting might be far more trouble than it's worth. Plus, you wouldn't be able to truly assess the results until it hardened. At that point, it's a little late to be fixing any problems that might have been hiding under there.

It may sound silly, and granted there isn't a whole lot about fiberglassing that could truly be considered enjoyable, but there is a certain satisfaction in seeing a freshly applied layer of glass that's been well done. Everything is down tight, free of defects and the entire surface has a uniform cloth texture, ready for filling. You can see that it's both structurally and cosmetically sound. I'd kind of miss that if I had to peel off a layer of other stuff to see what it left behind.

[boattruck]

Garnett, I use the soft yellow plastic squeegees, and don't seem to have any trouble with catching the edges, you will be moving the cloth into an ever smoother connection to the substrate, you want to watch that you don't move it to much, or have it tailored too close... if you have multiple pieces that will lap, I get one down and happy and then get the adjoining one down over it, if possible I leave the selvage edge on for these, as the never ending string thing makes me nuts! I do fill the weave with epoxy fairing rather than resin, I tend to use a putty type, such as Quik Fair or the like, as I think I can get it mixed up faster. As I mentioned through planning out the timing, I can usually get the fairing on while my resin is still partally cured.
Have some fun with it! Cheers, BT

[tomlarkin]

Garnett, a couple of planning things to think about:

• The pressure of having epoxy catalyzing in the pot makes you dumb. Do all your thinking about the processes ahead of time.
• As you plan your job, imagine you're going to be working with velco mittens on. For instance, if you tape your glass down, leave big tabs on the tape to be able to pull it off the glass easily. The glass will change size and shape as it wets out and you'll need to pull wrinkles out.
• Have a couple of paper towels already torn off the roll to wipe off sweat or drips.
• Have extra gloves handy and replace them if they get too sticky. I sometimes start out wearing two gloves per hand so I can strip the outer one off.
• Lay out all your tools and pre-cut pieces very carefully, with notes if you have many of them.
• After you finish the job, go back to it 15 minutes later. You can easily fix many issues when the glass is just firming up.
• It your part has an edge like the one below, let the cloth run past the edge, and slice off the extra when the epoxy is 'green', when it's easy to do. Leaving it until it's hard is a serious mistake - trust me!
• Avoid pre-cutting darts or holes in the cloth as much as possible. The glass is really shapable, especially if you remove the selvedge. Cuts and darts will start to unravel and be really hard to handle neatly. This piece is uncut:

[High Tide]

Great thread, love all the knowledge here. This saved me asking the same questions. Does it matter what brand of expoxy to use, or is it basicly how much you can fit into your budget?

[Garnett]

Tom, that looks like very valuable and very hard won praqctical advice - thanks a lot.

HT, I'm planning on using West Systems - it's £300 for 30kg - $500 for 7.5 gallons - so pretty expensive, but I can't find anything else, and it sounds like decent stuff.

[Welding Rod]

Go to a commercial chem supply and get crude epoxy. Its all the same stuff. The marine suppliers put in some additives to get certain properties.

When it kicks off and is done you can't tell them apart, just follow directions. Don't know cost now but it was 1/5 of the cost of west or sys 3.

I had 30 gals and I gave a little over $300.

[JimConlin]

Tom, that looks like very valuable and very hard won praqctical advice - thanks a lot.

HT, I'm planning on using West Systems - it's £300 for 30kg - $500 for 7.5 gallons - so pretty expensive, but I can't find anything else, and it sounds like decent stuff.

If you're in UK, SP Systems (owned by Gurit) Ampreg 22 is an excellent system. They offer quite a range of hardeners. I used it for a job where the layups took several hours to get together and the long open time made it possible. If you're as slow as I am, patient epoxy is a good thing.

The question of whether to spend the money for the 'brand name' epoxy systems has been discussed here at length. In my opinion, there are only two or three US suppliers of boatbuilding epoxy who know what they're doing- West System, (Gougeon Brothers), System Three and MAS. It's a very good idea to pick one and stay with it so you can learn how to control it.

[Garnett]

Crude epoxy.

What's that then? I need some googling terms! I cannot fin a cheaper epoxy here in the UK than the West stuff.

[Sailor]

How does a fiberglass newbie use less epoxy?


Build a smaller boat!

[JimConlin]

What's that then? I need some googling terms! I cannot fin a cheaper epoxy here in the UK than the West stuff.

http://www.gurit.com/

http://www.gurit.com/gurit-uk-isle-o...nd-hamble.aspx

[Welding Rod]

Try paint and industrial coatings.

As far as getting how to use it, might as well get used to using the cheap priced stuff. Epoxy is EPOXY. That is from the mouth of an industrial chemist. Paying more to have a boat or airplane on the label doesn't change the material.

[Todd Bradshaw]

Epoxy is EPOXY. That is from the mouth of an industrial chemist

I'm certainly not an industrial chemist, but I do know enough about epoxy resin to know that that statement is absolutely false. Want proof? Just look at the typical product lines of the common manufacturers, like Gougeon Brothers (WEST Epoxy) or System Three for example. Take the standard WEST 105/205 vs, their WEST G-Flex Epoxy. The two have very different flex, adhesion and creep characteristics. Different enough that each will likely fail when used for a job meant for the other one. Punch a hole in your rotomolded plastic kayak and a fiberglass patch made with G-Flex is one of the best ways possible to permanently repair it. Make the same patch with 105/205 and you get a patch that will eventually crack and/or delaminate if you can get it to stick at all in the first place. On the other side of the coin, build a hard-chine stitch-and-glue plywood dory with 105/205 fiberglass seam tapes and it should be around for decades. Substitute G-Flex for the resin and the seams will start to elongate and stretch from day one, because of the much higher creep of the more flexible resin. The better epoxy vendors can, and do, target specific applications for their products and adjust them accordingly. There is nothing wrong with generic epoxy, but there is no universal epoxy resin that works for any job, so you had better know what you're buying, what its characteristics are and what characteristics you need present.

There will also sometimes be drastic differences in resin clarity (if it matters for your project) in viscosity, and in the speed at which a particular resin will saturate cloth and/or want to run down the sides and onto the floor. These can be a big factors when you're trying to fiberglass a big object like a boat. Some of those other little addatives that the big brands throw in when they formulate a boat-building resin (like UV absorbers or hardeners geared toward specific weather or humidity conditions) may not always be absolutely critical to your job, but they are the product of building and testing boats, and obviously the manufacturers believe they're important enough to include.

So, though many different epoxy resins may share ingredients and some characteristics, the statement that they are all the same or that they all work equally well for any epoxy job is simply and quite obviously not true. It is entirely possible to choose the wrong resin for the job at hand, screw up a perfectly good boat and waste a pile of money in the process. This doesn't automatically mean that you need to purchase the most expensive resins available, but it does mean that you want to know what you are buying, what it's designed to do and what kind of track record it has in doing the job at hand. Resin cost is just a small part of the cost of building a wood/composite boat, even if all your labor hours are free. Trying to learn how to build a boat, how to fiberglass and trying to do it with resin that you don't know much about because some guy on the internet told you that they were all the same is not a very good formula for success.

The old discussion about them sticking a boat on the label and raising the price of resins, paint and other supplies that we all use comes up fairly frequently. I'm as frugal as anybody and make an attempt to avoid being the victim of this sort of marketing ploy. At the same time though, I see an awful lot of boats through my work, as well as the photos posted here on the forum over the past decade or more. I tend to be a hard-core perfectionist (as many of you are, no doubt, aware) and I find it interesting that the vast majority of the really primo, blue-ribbon boatbuilding and boat-finishing examples that we see (both amateur and professional) tend to be done with those materials that have a boat on the label or are specifically marketed for boatbuilding. Coincidence? Just a marketing gimmick? I'm not so sure.

[JimConlin]

+ 1

To reinforce the fact that there are considerable differences in epoxy products, See this representation of the range of Gougeon's pro-set epoxy line. http://www.prosetepoxy.com/laminating_epoxies.html
Note also the wealth of technical information about individual product pairings. Very few epoxy marketers know their product this well.

[the_gr8t_waldo]

i've found that to minimize the epoxie used, it's best to lay out the cloth in it's final position and let gravity iron it flat(at least two days- this assuming that a hull is being glassed bottom side up) without this ironing,creases require a bit more work to get it to lay flat and with that, the epoxie use increases . on the big day start by wetting out the wood, and don't stop untill it no longer is absorbing the epoxie and/or the epoxie starts to set up. at that point lay the cloth onto the project and wet it out. peelply layed over the works and lightly rolled into the matrix will foce the excess epoxie out and on to the surface of the pp, where once fully cured it's striped off and the excess epoxie is tossed with the pp. once that's done you can decide if you want to fill in the textured low points or knock down the high points.