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Thread: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

  1. #1
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    Default Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    I epoxied the 10oz cloth to my Simmons hull yesterday. But it took so long to get it all done (including entertaining the kids and running to store for more epoxy!), that I was not able to apply a second coat while the first was still hot. So the cloth is down but not filled and the epoxy is fully cured. Is that a problem? Will my second coat to fill the weave adhere properly? normally you'd need to abrade the epoxy to make a mechanical connection if it's fully cured, but I can't do that into the fiberglass.

    Also, assuming a 2nd coat ill be fine, do I need to wash this to remove amine blush? There's no way to really tell if there is any.

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    What brand and specific product of epoxy did you use? Does the manufacturer offer any guidance?

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    You can wash the cured laminate with water to remove any possible blush. Use a brush to get down in the weave pits.

    You can put the second coat over the cured laminate, you will not be able to tell any difference in the strength. Epoxy is so much better than everything else you will not be able to see the last 5%.
    OBTW, I just stepped in from doing the same thing.

    And really, you don't have any choice unless you want to remove the glass completely and start over. Not that hard to do if you are really concerned.
    Of course, if you finish the coatings (2) and find you don't like the job you can take it off then - or next year. Just a little more money and time.

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    It's West Systems. They have a very general section in the pamphlet I have on epoxying fiberglass that specifies, "apply second coat before first coat fully cures." But no details. I know with epoxy in general the hot 2nd coat adheres chemically and a 2nd coat over fully cured epoxy often requires sanding to get a good mechanical bond. I'll wash with hard plastic bristle brushes and green scrubbies ad hope that both cleans the blush and adds some tooth the cured epoxy.

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    I'm with upchurchmr

    If 207, it is blush free but washing can't hurt. West doesn't give a lot of detail for open times and for the home builder it makes it kinda tough. - the open weave provides a textured surface for mechanical bond and it does take several days for full cure. so you get a bit of both. I think of a fill coat as a fairing coat anyway.

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    A scrubbie will actually take off the epoxy if you get carried away.
    I would suggest just washing.

    No one including West can tell you what the strength reduction is. I also use West.

    The varnish or paint you use to protect the epoxy will have much less adhesion than epoxy on cured epoxy.
    Blush is very easy to remove but you want to get down into the pits, so don't use a really thick bristle brush.
    Typically I just use scissors to shorten up a cheap brush, that makes the bristles stiff enough and leaves them to get down in the pits.

    Don't overthink this.

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    It was 205/105 and I won't get back to it until this weekend so should "fully" cured by then. Thanks for all the advice though. Sounds like I'm ok with a quick wash down and fill.

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    after it gets tacky, otherwise you have to wash off the blush

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    You can still get a chemical bond as far as a week past initial cure, but you do want to wash the blush off before your next coat. On the other hand, don't get too hung up on the whole chemical bond (or not) thing. It is far less important (if at all) than most people seem to think it is. If folks would spend their time concentrating on measuring properly, mixing properly and avoiding stray chemical or solvent contamination instead of being so blindly focused on the elusive chemical bond, their epoxy work would turn out better. When was the last time you (or anybody else) saw a delam actually caused by inadequate chemical bond? Epoxy is very sticky stuff if you don't do anything dumb to screw it up.

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    Quote Originally Posted by Oldad View Post
    after it gets tacky, otherwise you have to wash off the blush
    Suggest you read the original post.

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    People tend to think of epoxy as paint, which it is not. People also whine about the blush that sometimes appears for no reason. It's easy to wash off! 4 coats usually fill the weave on 6oz. 10oz maybe more? 205 and 105 don't have the UV protection that 207 has. will you being painting the epoxy?
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...58#post3996158

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    You've got no problem. I first coated my latest build and let it thoroughly cure. Just washed it with water before applying second coat. No problems. In my opinion, the whole idea of "hot coating" has more do with avoiding the bother of removing amine blush and sanding the hull then it has to do with chemical bonding. Most home builders, working at night or with limited time, simply don't have the time to apply multiple coats of epoxy all at once.
    I was born on a wooden boat that I built myself.

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    todd is right. Epoxies take over a week to cure completely. From the epoxy point of view, not much difference between 1 day cure and 2 days of curing. of course, you should not be using a blushing epoxy......

    paul oman
    progressive epoxy polymers inc

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    Quote Originally Posted by Phil Y View Post
    Suggest you read the original post.
    Good God, now I have two people telling me when I'm wrong. I have to tolerate my wife, but you, Phil? Now where is my emoji with the upraised middle finger….

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    Just to be kind I won't be the third to tell you there was something you missed.

    What's the big deal?
    I personally NEED to be corrected once in a while - not the end of the world or even something to be bothered about for more than 5 minutes.
    Mostly we don't keep score here - mostly.

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    I actually don't normally try to do hot 2nd coats. I just sand to get rid of minor blush and put some tooth into the smooth surface for a good bond. In this case I can't sand because it would take off the cloth! I was assuming there might be a loss of bond in epoxy down in the dimples of the weave. Seems silly now. And even more so after looking at the cloth again yesterday... it seems much rougher now then when it was still tacky so I think adhesion is a non issue. But there is some blush to wash off.

    I'm curious about the number of coats to fill the weave though. I had some extra epoxy in my cup at the end and smoothed it out over a small section and it's almost fully filled at this point, maybe a very light third coat would be needed. 5 plus coats to fill seems like too much?

    Yes I will be painting the bottom. There will be a follow up post with all sorts of other silly questions for that one!

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    Quote Originally Posted by upchurchmr View Post
    Just to be kind I won't be the third to tell you there was something you missed.

    What's the big deal?
    I personally NEED to be corrected once in a while - not the end of the world or even something to be bothered about for more than 5 minutes.
    Mostly we don't keep score here - mostly.
    No big deal, just seemed unnecessary to point out the obvious. I was only trying to be helpful and badly misread the original posting—and the heading as well. Seemed a bit pedantic to point out my mistake, but then some folks can't resist—take my wife—please…
    Last edited by Oldad; 05-24-2016 at 02:44 PM. Reason: bad spelling

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    Quote Originally Posted by dmede View Post
    I just sand to get rid of minor blush and put some tooth into the smooth surface for a good bond.
    From what I've read on the forum, sanding won't remove blush; it will just embed it into the scratches. I usually do a quick rinse with a wet rag or sponge before doing anything.
    “It doesn’t matter how slowly you go -- so long as you do not stop.”
    -Confucius

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    I am not a big fan of using loads of resin in an attempt to fill the weave. Sooner or later you will still need to fair the glass. So you may as well begin now by using resin and fairing compounds such as the microlight or microballons at this stage and kill two birds with one stone. Apply your fairing with cement trowels, spreading it across a larger area in lieu of those small squeezies. It will go further with less resin with additional weight savings too. Oh as far as the task of sanding, well you can take a wire brush and go over the surface too if you plan on fairing it at this stage. This will not harm the glass if you just use some finesse with it.
    WBF=DNC

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    Quote Originally Posted by erster View Post
    I am not a big fan of using loads of resin in an attempt to fill the weave. Sooner or later you will still need to fair the glass. So you may as well begin now by using resin and fairing compounds such as the microlight or microballons at this stage and kill two birds with one stone. Apply your fairing with cement trowels, spreading it across a larger area in lieu of those small squeezies. It will go further with less resin with additional weight savings too. Oh as far as the task of sanding, well you can take a wire brush and go over the surface too if you plan on fairing it at this stage. This will not harm the glass if you just use some finesse with it.

    Yes indeed.

    skim the impregnated glass fabric with lightweight fairing compound ....or if secondary bonding may be needed , a rolled on slurry of thickened epoxy

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    Great point about using fairing compound and epoxy to fill the weave. Makes the epoxy go farther. Need to consider what filler to use to make the fairing compound. Some sand much easier than others. I never liked Quickfair although have friends who swear by it.

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    Home mix is difficult. Get the mix ratio wrong..resin rich, resin dry....and you make much work

    pre mix like Awlfair is correctly blended.

    if you mix your own..be scientific, accurate...and always compare the finished product against premix until you find your magic formula.

    Microlight filler from west is a good starting point

    small batches of fairing compound are very difficult to get right.

    home brew is best for big bog jobs, then shift to premix for final fill and fair.

    One way to avoid waste when using expensive pre mix is to transfer part a into an empty caulking tube ...and part b into an empty tube

    to mix squeeze out the appropriate length worm of part A bog... then next to it squeze out the correct length worm of part B bog...then combine

    Accurate..clean...small batch..little waste.

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    I usually use 2 coats of epoxy, but I am trying to do a varnished surface. And I use 6 oz. You really just need to try it out - 1 extra coat over whatever fills the weave - to get enough to sand.

    BUT, with paint you can fill with fairing compound like the guys say. Much less work overall and it saves epoxy.

    Oldad, didn't mean to pick on you, sorry.

    Quote Originally Posted by dmede View Post
    I actually don't normally try to do hot 2nd coats. I just sand to get rid of minor blush and put some tooth into the smooth surface for a good bond. In this case I can't sand because it would take off the cloth! I was assuming there might be a loss of bond in epoxy down in the dimples of the weave. Seems silly now. And even more so after looking at the cloth again yesterday... it seems much rougher now then when it was still tacky so I think adhesion is a non issue. But there is some blush to wash off.

    I'm curious about the number of coats to fill the weave though. I had some extra epoxy in my cup at the end and smoothed it out over a small section and it's almost fully filled at this point, maybe a very light third coat would be needed. 5 plus coats to fill seems like too much?

    Yes I will be painting the bottom. There will be a follow up post with all sorts of other silly questions for that one!

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    What I meant by sanding off minor blush was basically that unless there is a noticeable amount of blush, I don't ever find a need to wash it. Most of the time my epoxy surfaces seem to cure dry and tack fee, but occasionally will have a good deal of waxy amine blush on them (usually with the clear finish epoxy).

    Interesting idea to fill the glass with a fairing mix. I used the West 410 microlight to fair the panels before laying down the glass. It goes on well and sands off easy. I may roll on one light coat of regular epoxy to even things out and fill the bottom of the glass then top that with a faring coat to finish.

    After the first coat to wet the glass and adhere it to the panels, I noticed that it seemed to take much less epoxy to start to fill the weave.

    Before I do any of this though, I need to add glass patch pieces to the inside of my motor well.

    Thanks for the tips all.

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    Quote Originally Posted by Oldad View Post
    No big deal, just seemed unnecessary to point out the obvious. I was only trying to be helpful and badly misread the original posting—and the heading as well. Seemed a bit pedantic to point out my mistake, but then some folks can't resist—take my wife—please…
    Is she pretty?��

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    I just sand to get rid of minor blush and put some tooth into the smooth surface for a good bond.
    This is absolutely the wrong way to go and probably does more harm than good.

    What I meant by sanding off minor blush was basically that unless there is a noticeable amount of blush, I don't ever find a need to wash it.
    Find the need. To not do so is a stupid risk you don't want to take. Even with non-blushing epoxy it is a good idea to wash it if it's been sitting for a few days unless you have an incredibly clean shop. Chances are that something may have settled or been deposited on the surface that you don't want in your boat (dust, oils, byproducts of car exhaust, etc.) An amazing number of the problems with epoxy resin are directly created by the builders, not the resin.

    The criteria I use for filling with straight resin or with filler mixes is the need for durability and abrasion resistance. A resin fill is a lot tougher than a mixture if you're likely to beach the boat or hit rocks. Resin filling is done using however many coats it takes to totally hide the weave, plus one more as a sanding cushion. That allows me to sand it smooth without cutting into the weave. Ideally, fillers containing microballoons (which is most of them) should be topcoated with a coat or two of plain resin, then sanded and painted. Sanding exposed microballoons leaves a surface with a lot of very tiny, cut-open balloons, filled with air. Your paint will bridge the gaps, rather than fill them. If it later heats up from the sun, these spots can pop their skinned over paint coverings, leaving lots of little ugly pinholes in your paint job. They're a real bitch to fix.

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    I respectfully disagree with everyone here. You now have a major task ahead of you.

    Start by washing the amine blush off the epoxy. Use only distilled deionised water and be sure to rinse three times. Dry the surface with warm filtered air. When the surface is dry begin your sanding. Buy a box of toothpicks, some 600 grit sand paper, a bottle of cyanoacrylate super glue and a pair ox 20x magnifying glasses Wearing the magnifying lenses carefully glue a piece of 600 grit paper to the small end of each toothpick. Then use the toothpicks to sand carefully inside the indentations in the cloth's weave taking care not to sand through the epoxy coating on the glass fabric. If you expose glass fibers at any point, immediately apply a new coating of epoxy to the exposed glass fibers with an artists brush. Mark the area so you can sand it because it will surely cure before you finish the sanding job. If the sanding takes more than one day, be sure to wash off new amine blush before starting sanding on each subsequent day until 10 days past initial epoxy application. Upon completion of sanding, vacuum the surface and wash it thoroughly to remove all contamination you introduced during sanding. Dry with filtered air, then recoat with epoxy. When using epoxy it is essential to remove air that gets mixed into the epoxy during mixing. To do that place the mixed epoxy in a vacuum bell jar and apply vacuum down to 0.03 microns pressure until the epoxy mixture is completely degassed. You will have to apply vacuum slowly at first to avoid having the epoxy foam. Since you will not be able to avoid mixing air into the epoxy during application, apply a layer of release fabric, a breather fabric and a vacuum bag to the freshly epoxied surface and pump the vacuum bag to a hard vacuum until the epoxy cures. Repeat coating procedure as needed until the weave of the fabric is filled with epoxy.
    Last edited by Todd D; 05-24-2016 at 07:49 PM.

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    Holey moley, never realised we were making space craft.

    I not so respectfully disagree. Lets see, about 100 fabric peaks per square inch?
    How many square inches? lets just approximate like this was a kayak (what I know).
    16'x 2' wide. Thats about 60" around the circumference x 16 x 12 = 11520 square inches, but the boat tapers. I'll estimate only 40% of that calculation = 4,680 square inches x 100 pits / sq in= 468,000 pits

    As a practical matter I would suggest you pull off the glass and start again instead of going thru this "procedure".

    Or call the Gougeons at West system and ask them what to do as a "practical" matter. Only a few of us have their expertise - forget about the amateurs here (that includes myself - what do I know)

    Of course I have made the same mistake in the past and successfully completed a boat with much less xxxxxxxxx.

    Can you imagine cleaning out and hand painting over 400,000 pits??????

    WAIT, I JUST REALIZED I'VE BEEN TROLLED. What an IDIOT I AM.
    And what a great job of sarcasm. I Apologize to everyone.

    Where is the emoticon for embarassed?
    Last edited by upchurchmr; 05-24-2016 at 11:36 PM. Reason: Realized what a sucker I am.

  29. #29
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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    Quote Originally Posted by Phil Y View Post
    Is she pretty?��
    Yes, very pretty, corrects me al the time but I wouldn't give er up for anything. I often ponder the question: If a man speaks and his wife is not there, is he still wrong?

  30. #30
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    Wink Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    Quote Originally Posted by Todd D View Post
    I respectfully disagree with everyone here. You now have a major task ahead of you.

    Start by washing the amine blush off the epoxy. Use only distilled deionised water and be sure to rinse three times. Dry the surface with warm filtered air. When the surface is dry begin your sanding. Buy a box of toothpicks, some 600 grit sand paper, a bottle of cyanoacrylate super glue and a pair ox 20x magnifying glasses Wearing the magnifying lenses carefully glue a piece of 600 grit paper to the small end of each toothpick. Then use the toothpicks to sand carefully inside the indentations in the cloth's weave taking care not to sand through the epoxy coating on the glass fabric. If you expose glass fibers at any point, immediately apply a new coating of epoxy to the exposed glass fibers with an artists brush. Mark the area so you can sand it because it will surely cure before you finish the sanding job. If the sanding takes more than one day, be sure to wash off new amine blush before starting sanding on each subsequent day until 10 days past initial epoxy application. Upon completion of sanding, vacuum the surface and wash it thoroughly to remove all contamination you introduced during sanding. Dry with filtered air, then recoat with epoxy. When using epoxy it is essential to remove air that gets mixed into the epoxy during mixing. To do that place the mixed epoxy in a vacuum bell jar and apply vacuum down to 0.03 microns pressure until the epoxy mixture is completely degassed. You will have to apply vacuum slowly at first to avoid having the epoxy foam. Since you will not be able to avoid mixing air into the epoxy during application, apply a layer of release fabric, a breather fabric and a vacuum bag to the freshly epoxied surface and pump the vacuum bag to a hard vacuum until the epoxy cures. Repeat coating procedure as needed until the weave of the fabric is filled with epoxy.
    Very well done, Especially the drying with filtered air!

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    Quote Originally Posted by Oldad View Post
    Yes, very pretty, corrects me al the time but I wouldn't give er up for anything. I often ponder the question: If a man speaks and his wife is not there, is he still wrong?
    If a man speaks and his wife doesn't respond, did he even speak?

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    Quote Originally Posted by Todd D View Post
    I respectfully disagree with everyone here. You now have a major task ahead of you.

    Start by washing the amine blush off the epoxy. Use only distilled deionised water and be sure to rinse three times. Dry the surface with warm filtered air. When the surface is dry begin your sanding. Buy a box of toothpicks, some 600 grit sand paper, a bottle of cyanoacrylate super glue and a pair ox 20x magnifying glasses Wearing the magnifying lenses carefully glue a piece of 600 grit paper to the small end of each toothpick. Then use the toothpicks to sand carefully inside the indentations in the cloth's weave taking care not to sand through the epoxy coating on the glass fabric. If you expose glass fibers at any point, immediately apply a new coating of epoxy to the exposed glass fibers with an artists brush. Mark the area so you can sand it because it will surely cure before you finish the sanding job. If the sanding takes more than one day, be sure to wash off new amine blush before starting sanding on each subsequent day until 10 days past initial epoxy application. Upon completion of sanding, vacuum the surface and wash it thoroughly to remove all contamination you introduced during sanding. Dry with filtered air, then recoat with epoxy. When using epoxy it is essential to remove air that gets mixed into the epoxy during mixing. To do that place the mixed epoxy in a vacuum bell jar and apply vacuum down to 0.03 microns pressure until the epoxy mixture is completely degassed. You will have to apply vacuum slowly at first to avoid having the epoxy foam. Since you will not be able to avoid mixing air into the epoxy during application, apply a layer of release fabric, a breather fabric and a vacuum bag to the freshly epoxied surface and pump the vacuum bag to a hard vacuum until the epoxy cures. Repeat coating procedure as needed until the weave of the fabric is filled with epoxy.
    Thanks, Todd. That's how I was planning to do it, except I don't use vacuum equipment. I'm going to build a 30 foot hyperbaric chamber to compress the air bubbles to oblivion. I'm pretty sure epoxy's tensile strength will be sufficient to maintain the compressed micro-bubbles. Also, why use a toothpick when you can buy a micro dremel? ....

    As for the question about how many coats, I'll throw out an example from the last few weeks.

    2 layers of 6 oz fabric on a bottom. I wetted the first layer, applied a second layer within 8 hours and wetted that--both times with a spreader. Then left things for a week because I was busy. Washed it down with water and scrubbies and applied a coat with a high density foam roller. A few days later, washed again, and applied another coat with another roller.

    I kept doing that over the course of time when I had time. Last evening was the fifth application, and the weave is pretty much all filled except for a few spots.

    (Alas, I really didn't use toothpicks, microdremels, vacuum or pressure, etc. I guess I'm resigned to it all falling off somewhere).
    Last edited by VictorBravo; 05-25-2016 at 05:53 PM.

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    Can someone explain why one needs to fill the weave. I understand if you need it smooth ie boat bottom. What about if doing the inside and doesn't need to be smooth. How many coats then?

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    As many as you want or don't want.

    More epoxy will not add to the strength.
    Unfilled epoxy will scrape the skin off your feet/ arms/ legs.
    Unfilled will trap dirt immediatly.

    Whatever you want.

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    Default Re: Apply 2nd coat epoxy to fill cloth weave after 1st coat is dry?

    If you don't mind the look of the cloth weave and the cloth is down tight to the surface and properly saturated, an inside surface is generally fine with no filler coats at all. It makes for a pretty good non-skid surface and the highest possible cloth to resin weight ratio. If it's exposed it still needs a UV protective coat or two of paint or varnish, but with the right squeegee it is possible to generate a very clean looking and uniform cloth texture over a large area. As mentioned, it may pick up dirt, and that stuff is hard to wash out. With a soft squeegee (like a thin slab of ethafoam packing foam) it is possible to squeegee out a thin, partial filler coat. This fills the deepest parts of the weave texture, but will still leave some non-skid and look uniform in texture.

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