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Thread: alternative to epoxy for fairing?

  1. #1

    Default alternative to epoxy for fairing?

    in my previous post i talked about my poor tape job, actually its not as bad as i thought. i am however completely DONE using epoxy for ANYTHING! i have mixed about 12-13 batches of epoxy/cabosil/microballons and i find it terrible for fairing, no combination of ratio works well. if it goes on well it sags, if it doesnt sag it goes on like damp sawdust. can i use marine "bondo"? what about polyester resin/talc? i have painted a couple of cars and a dozen or more motorcycles so getting a fair surface isnt new to me. if i cant find a different product my current alternative is a bon fire. thanks.
    Last edited by rodjr; 06-05-2011 at 07:20 PM.

  2. #2
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    Default Re: alternative to epoxy for fairing?

    You might try it without the Cabosil. I use epoxy with phenolic microballoons and it works fine for me.

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    Default Re: alternative to epoxy for fairing?

    All thickeners are not the same. There are fibers like chopped cotten, chopped glass and wood flour for strength. Fumed silica (Cabosil among others) for hardness and microballoons for ease of sanding.

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    Default Re: alternative to epoxy for fairing?

    R, A little exitable perhaps! Epoxy, while sticky and toxic,is not the devil... ( dont eat it, or rub it on your chest...)
    If you do want to make fairing compound with your resin, you want to use microballoons, mixing in the red( or sometimes white) ultra light powder until you arrive at the perfect mix that will spread but still hang( it can take a while). It can be done. I, in recent years, have taken to buying epoxy fairing compound, a two part mix that, well mixed, will yeald a beutiful smooth fairing compound. The brand I can find locally is Silver Tip Quick Fair, I believe it is System Three brand. In any case, the key is to 'keep you head , when all about you are losing theirs'... wishing you well, BT

  5. #5

    Default Re: alternative to epoxy for fairing?

    i dont doubt it can be done, many seem to do it. epoxy is not for me, i find the stuff exhausting in every way. im not impressed with it. now the brown resin glue works great. i intend to build more boats in the future (i have several sets of plans) but epoxy is out. will polyester resin work over epoxy? on future boats i will use the polyester through and through. i have used it before and find it much more freindly, so i would like to switch now.

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    Default Re: alternative to epoxy for fairing?

    You have used epoxy incorrectly by using the wrong filler.

    west 407 is for fairing (red) . sands easily
    west 410 is for ultra fairing(beige). sands VERY easily, only recommended for very thin application.


    If you glue stuff with fairing fillers, it will break. If you try to fair with gluing fillers,well, that you now know .

  7. #7

    Default Re: alternative to epoxy for fairing?

    i am using microballons for fairing, is this incorrect? i tried a couple batches where i added very small amounts of cabosil as suggested in another thread.

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    Default Re: alternative to epoxy for fairing?

    Sounds like you haven't been having much fun here rodjr, I wonder if you might not benefit from sitting down with someone more familiar with epoxy and look at how you're working. Epoxy really is far superior to polyester in so many ways, from not smelling as badly through being stronger, more flexible, with better adhesion, better water resistance and on and on. There's many reasons why epoxy has replaced polyester in boat building.

    For fairing, I use micro balloons which are microscopic balls. Being balls they don't hold within the epoxy as well as micro fibers or wood flour which have jagged edges and also absorb the resin. Micro balloons therefore sand much easier and give a really nice smooth finish at the expense of requiring a much thicker mix to start with - the very thing which makes them easy to sand also makes the goop slump much more so you need to mix it up more like an icing sugar than peanut butter consistency.

    Polyster on the other hand doesn't adhere anywhere near as well and has a greater shrinkage than epoxy - up to 7%- and takes much longer to cure. You run the risk of having your lovely fairing work shrink away from the surface a few weeks after you thought you had finished. It's far more likely to blister from water absorption as well. In short .... horrible stuff.

    Honestly rodjr, stick with it, watch others using it and figure out what it is they do which you're not. It sure isn't as nice to work with as honest timber and clever carpentry, but it leaves polyester in the shade.

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    Default Re: alternative to epoxy for fairing?

    Yep, your "problems" with epoxy are completely due to not being familiar with the products and how to combine/use them. I don't know about you, but most of us weren't born with the knowledge of how to use epoxy systems correctly and to do so took some studying. You can do what you want, but if you want to be serious about building wood/composite boats, some time with your nose burried in a couple of good books on epoxy boat work (The Gougeon Brothers on Boat Construction is the best) would be well worth your time. Since polyester doesn't seal wood well, or in most cases even stick to wood well, you can pretty much bet that it will probably fail and not be worth wasting your time or money on. You could always swear-off composite building and go traditional, old style, but complaining about and blaming the epoxy when you haven't yet learned how to use it, and claiming you're switching to polyester isn't very bright and certainly isn't a formula for success.

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    Default Re: alternative to epoxy for fairing?

    +1 on try, try again. You'll get it. I might add that part of the art of this lies in the mix of fillers; another part lies in the cure rate. In my experience, epoxy mixtures get thinnner a few minutes intp cure, than start to tighten up. So there is a "sweet spot" in both mix AND when to start filetng after mixing. ( and when to quit if the batch your using gets too stiff/too far into cure.

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    Default Re: alternative to epoxy for fairing?

    rodjr: if your final surface is to be painted why not use Interlux Surfacing Putty on bare wood? It feathters out just like automotive bondo. Jeez, all this epoxy crap for above waterline use drives me nuts. It's expensive hocus pocus that make no sense.
    "Whiskey is for drinking, water is for fighting over." -Samuel Clemens

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    Default Re: alternative to epoxy for fairing?

    Ditto that. Evercoat or a good High build primer can cover a lot of sins.

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    Default Re: alternative to epoxy for fairing?

    If you don't have good luck mixing your own, I would recommend a pre mixed epoxy fairing compound. Interlux makes one (or did) for above or below the waterline. It was the perfect consistency, didn't sag, went on very smooth. Good Luck.

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    Default Re: alternative to epoxy for fairing?

    +1 on the pre mixed epoxy fairing compound. Having mixed my own for years I will now not bother as the pre mixed is far nicer to use.

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    Default Re: alternative to epoxy for fairing?

    Quickfair. IMHO, this product is optimal for your task.


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    Default Re: alternative to epoxy for fairing?

    I am not a epoxy fan either, actually I avoid it everywhere I can. I have a really bad skin reaction when using it also...

    Polyester don't stick on top of epoxy, once you started with epoxy you have to go all the way with it. For wood you can use Resorcinol as a alternative to epoxy, lot less toxic to work with and clean with water when not cure which is handy to clean tools, gloves etc...but require a tight fit and heat to cure (Electric blanket).

    You've started with epoxy, so you got to finish it with it.
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    Default Re: alternative to epoxy for fairing?

    I would add that smaller batches of epoxy/microballons were key for me. Larger batches hold heat and kick off quicker. I mix a small amount of epoxy, quickly add filler, and transfer to a plastic board and spread it out to help cool it and slow curing. I have also used a piece of sheet metal as a palette. Your mileage may vary...

    JHP

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    Default Re: alternative to epoxy for fairing?

    Because the bubbles are good insulators, the heat of epoxy curing is retained and a mass of bog can cure more quickly than you want. Because of this, I generally use slow hardener and with large batches a plasterer's hawk will help dissipate heat.

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    Default Re: alternative to epoxy for fairing?

    Quote Originally Posted by yzer View Post
    rodjr: if your final surface is to be painted why not use Interlux Surfacing Putty on bare wood? It feathters out just like automotive bondo. Jeez, all this epoxy crap for above waterline use drives me nuts. It's expensive hocus pocus that make no sense.
    Or how about just sanding so the surface doesn't need to be faired? I must be missing something.

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    Default Re: alternative to epoxy for fairing?

    I feel your pain. I experienced the same thing a couple of summers ago. My problem was the result of trying to fair over 12 ounce biaxial fabric, which is way overkill for my small boat.

    My advice: Mix in small batches, wash off the amine blush between coats or the new ones will not stick. To prevent sag, I rotated the hull so it was not so vertical. That helped the most. The goal is to avoid sanding as much as possible. The right mixture of microballoons and cabosil will take time and experimentation.

    That Quick Fair looks very promising.

    Hang in there; don't give up. Polyester is not an option.

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    Default Re: alternative to epoxy for fairing?

    I too was wondering how much of the hull you actually need to fair... usually fairing is applied areas where you could not sand the underlying material smoothly.

    Epoxy is not difficult to work with at all... but there is a learning curve and you have to expend some effort in getting the "feel" of the product... and towards working with common sense organization in your work flow and "working clean". Some good advice above...but perhaps its best to think back when we all started and remember the small details left out that caused us all to make a few mistakes and learn some hard way.

    This may make it clear to you... when you first start working with epoxy, you tend to mix smaller batches and use medium or slow hardener to give you time to make the application... but... as you progress in product knowledge and application techniques and skill, you will tend to use fast hardener most of the time because it just goes off faster and saves you tons of time and most important of all, you have developed your skill in epoxy application to the point that you do not need much time to achieve a quality application. Naturally, this depends on the job you are doing because some applications require slow hardener or medium because the task required takes a bit of time.

    For fairing I use a mixture of half cabosil, and about 40% talc, and 10% wood flour. I mix to the consistency close to peanut butter. I use talc because unlike microbaloons, when sanded you get a nice smooth finish... whereas micro-baloons get sanded in half... and need to be coated with epoxy to fill the voids. Don't be afraid to do some testing with mixtures and be consistent and keep track of exactly how you mixed the test compound. With experience, you will learn to just apply the cabosil and the other thickeners till you get the feel you want of the fairing compound. Cabosil is required because of its thixotrophic nature, which is necessary to keep the epoxy from sagging. Many times I use cabosil and talc about even in ratio.... but usually mix a bit more talc (Johnsons Baby Powder that says talc is main ingredient) because it makes for easier sanding.

    Probably, the best advice above other than taking time to learn about epoxy in general.... is to buy the pre-mixed mentioned above from System Three. It costs more than you mixing your own, and you can take your time learning to mix your own over time. Sometimes the time saved with pre-mixed products is money well spent.

    Get the System Three Epoxy Manual (free pdf online) and "The Gougeon Brothers on Boat Construction"... and try to lose the negative attititude towards epoxy. Epoxy makes things possible that you cannot imagine once you learn all of it's abilities and how to use it. Find someone who you can use as a mentor in these initial stages so that you can make a call and save the time and wasted efforts from a simple mistake. You can always ask here on the forum or pm some of the more knowledgable guys.

    One more thing, when fairing use a smooth 6" squeege and/or a 4" or 6" metal putty knife and constantly keep it clean with an old disposable rag so that each time you make a stroke with the squeege or knife, you get a perfectly smooth surface. If you fail to wipe off the contact surface of your fairing tool, you will have problems getting a nice fair result. Remember, epoxy is not all that easy to sand so when you are fairing you try to get as smooth a finish as reasonable when using the fairing tools.... then sanding will be minimized.

    Good luck,

    RodB
    Last edited by RodB; 06-06-2011 at 03:48 PM.

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    Default Re: alternative to epoxy for fairing?

    Quote Originally Posted by jalmberg View Post
    Or how about just sanding so the surface doesn't need to be faired? I must be missing something.
    Oh... found the previous thread. One thing a newbie should try to do is to make mistakes slowly. Sounds like the main tool needed for this project is patience.

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    Default Re: alternative to epoxy for fairing?

    I find that I have the best result using straight red balloons and using several very thin coats rather than trying to put on much at once. If I put it on too thick then it sags.
    I ended up using four or five coats to do what i would have done in one pass using bondo on a car body.


    i feel your fairing pain,

    Jerry

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    Default Re: alternative to epoxy for fairing?

    If it sags, you need more filler in it. The mixture of resin to balloons for good fairing compound has a little bit of resin and a rather large pile of balloons. Make a test sample, mix it up, stick some on a board and let it sit there for half an hour. If it sags at all, you need more filler and you want to keep track of the amount you're adding so that you can duplicate that proper mix once you find it with your tests. As with any highly-filled resin mixture (home-brewed or commercial) you also want to pre-coat the wood with plain resin/hardener first, because high amounts of most fillers reduce the adhesive qualities of the resin mixture. Usually, this can be done just minutes before you start filling. Mix a bit more resin and hardener than you need, give the area a quick, thin coat and them mix your filler in and start filling. There is nothing mysterious about it.

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    Default Re: alternative to epoxy for fairing?

    When I have a significant depth to fill (1/8" or more) over more than a square foot, I'll apply the bog with a notched spreader. There are plastic notched spreaders at the big box for applying flooring mastic and West System has some nice little plastic spreaders that are about 4" square. The notched spreaders offer better control of depth than a flat spreader and lay down half as much material for a given depth. When the notched spreader bog has cured, sand the ridges to the desired contour with a longboard or an appropriately large block and coarse paper. Because you only have 50% coverage, the sanding will be quite easy. It'll look like noodles on the surface. Get the loose dust out with a vac or airhose, then with a smooth spreader or drywall knife, spread bog into the grooves between the noodles.
    This method save a lot of material and a lot of effort and is applicable to Quickfair or 'mother's recipe" bog.

    I prefer quartz microspheres to phenolic microballoons, mostly because they're half the price. A 5 gallon bucket is about $40. When I think of it a little cabosil makes the bog smoother and less apt to slump.
    Last edited by JimConlin; 06-06-2011 at 08:22 PM.

  26. #26

    Default Re: alternative to epoxy for fairing?

    at this point i have about 90hrs and $160 worth of epoxy supply's invested in fairing the inside only of a 9' boat. i spent 11hrs on it today and my luck has not turned. im going to grind out all the tape, most of the fillet material, then redo the fillets much fatter. then ill cut my own tape from 4 oz cloth and do 2 layers, one wider than the first to blend better than 1 layer of the premade 6oz tape. then i think ill just use multiple coats of unthickened epoxy to build up, and sand it all in. im sure all of that will be less trouble than finishing it this way. or it may even be just as easy to cut out a strongback, frames, etc, and glue, screw and nail together a conventional construction boat. thank you for all the suggestions, i assure you i tried many today.

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    Default Re: alternative to epoxy for fairing?

    Your hours and money spent do not reflect accurately on how well epoxy can work. For twice the money and half the time I built this.

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    Default Re: alternative to epoxy for fairing?

    @wizband it look like a big shoe, where is the other one?
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    Default Re: alternative to epoxy for fairing?

    Rod, Hate to see you bouncing all over the place, swearing off this or that material...Slow down, relax, it will be OK, this is not, as they say a piano...I encourage you to do whatever seems best to you, but your last post sounds like you are lining yourself up for more hard times, first, taking the tape out will not be an easy feat,you will likely be taking out some of your plywood with it...second, while two tapes are fine, cutting your own tapes, in my experience leads to tough layups, I much prefer to work with premade tapes ( say a 3" and a 5") as the selvage edge doesn't unravel, leading to threads pulling out helter-skelter as you are laminating, I can already see the veins poking out of yer neck from here!
    A reasonably workman like tape job will look just fine with no fairing at all under a coat or two of paint. wishing you well, Cheers, BT

  30. #30

    Default Re: alternative to epoxy for fairing?

    unfortunately at this point most of the original tape is very, very thin from all the sanding/filling disasters so more tape will be needed to hold the boat together anyway. doesnt seam a good idea to put another layer over an unfair microballon/ thin tape joint. so repairs are needed to move on.

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    Default Re: alternative to epoxy for fairing?

    What are you building rodgr,( excuse me for not knowing). My 40mph" shoe" has no tape. Filets only. It lands /works harder than any rowboat and most sailboats.

  32. #32

    Default Re: alternative to epoxy for fairing?

    the project in progress is a selway fisher stornoway 9, 11 planks total so lots of seams. some of the seams are nearly flat so the fillets are just large enough to let me get the wire out before i taped. im trying to get a new attitude, so today im just using the boat as a sacrificial lamb. ill keep trying on a few seams until i get it, when im certain i can produce the results im looking for ill start a new boat. ill keep this one around and if i run into trouble in another area, ill practice on the "test mule" instead of killing a good project.

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    Default Re: alternative to epoxy for fairing?

    Going forward (I am inferring that you are facing further work with epoxy), use automotive tape and paper to mask areas that you are epoxying, and remove those items while the pox is wet. If you don't, you'll have a second set of problems getting tape and paper off, which will also mar the wood (two problems for every solution, as my uncle used to say). I have found that careful prep before application goes miles over trying to finish and fair after the fact. I too am an amateur poor at fairing, though at this stage it is aggravation and not unfamiliarity with the process. I get focused on my next build and then half-ass the finish work. I am nearing finishing stage of a Coquina and I am going to have to really confront these issues myself, or wind up with a workboat finish on a masterpiece design. You've got some advice here from some guys doing brilliant work though!
    Last edited by davebrown; 06-09-2011 at 11:43 PM.

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    Default Re: alternative to epoxy for fairing?


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    Default Re: alternative to epoxy for fairing?

    I'd avoided this thread but took a look -- so I guess the answer to your question is "no", as none has been suggested

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