Teardrops n Tiny Travel Trailers

Hi all,
I had checking issues with my original weatherproofing so had to strip down to the wood. Now I am using fibreglass/epoxy to seal it (hopefully) for good. Because the shell is built I have to glass the walls vertically.

So I want to thicken the epoxy a bit and make it easier to sand when filling the weave. I don’t think I’ll thicken when saturating the glass. I’ll use a combo of microspheres and colloidal silica. If anyone has done this can you please recommend a ratio (by volume) for the 3 components? Ballpark will do. Would the ratio be different for horizontal surfaces?

Thanks in advance, this board has been a valuable resource for my build!

Bret


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many get suckered into using the high priced spread when poxifying glass fiber

1st off you need to dedicate some TIME for this step

then you begin w/ pre-coating the wood w/ pox using a squeegee

i like the yellow ones from the auto paint n body supply store



using a brush get the pox on the wood and spread it w/ the squeegee

allow to just get tacky

spread out your glass cloth and squeegee a thin coat of un-thickened pox to eliminate all white unsaturated cloth

allow to become just beyond tacky butt knot yet cured and apply another coat of pox w/ the brush/squeegee method

when this coat has almost cured mix a light slurry of pox and wood flour(not saw dust) and apply it the same brush/squeegee method

repeat until the fibers are filled then do one more coat of un-thickened pox

allow to cure and sand for your chosen final finish

wood flour can be had from duckworksbbs.com for chump change

the time for the pox to almost cure depends on the hardener speed along w/ the temp & humidity

if you allow the pox to cure between coats you will have to wash the blush off and sand it before re-coating which is a major PITA

this process is called HOT COATING and drastically reduces your overall labor time

BON CHANCE

sw

Thanks for the info, I appreciate you passing on your methods and experiences. However, I already have the glass microspheres and colloidal silica (and wood flour) and I would prefer to use the combo because I already purchased the materials. And at least where I am, the cost was very reasonable (<$20 cdn for enough to do what I need to do). The wood flour wasn’t a whole lot cheaper. Plus I like the idea of bulking up the epoxy with microspheres so that the weave can be more easily filled, along with low spots, etc. It sounds like it should be easier to sand as well.

So if anyone has experience using this combo, please enlighten me.

Bret


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Colloidal silica is used to thicken epoxy when you want to use it as a glue you don't plan to sand. It toughens epoxy. The microballoons make it easier to sand but compromises the strength as an adhesive.

What I've always done is fair the surface and fill small dents with epoxy/microballoons mixing as much microballoons as needed to make a putty; 75% or more microballoons. This will set up much faster that epoxy alone so don't make more than you use in several minutes.

I've always applied cloth over dry wood but I'm used to compound curves on boat hulls so you really have to get the glass to lie flat before you wet it. Apply epoxy with a foam roller maybe a couple feet at a time. Keep looking back at the areas you've done and wet out any dry spots as you go.

Before the epoxy sets, scrape the excess off. This pushes the glass against the wood and dramatically reduces the need for later sanding. Depending on how fast your epoxy is this can be a frantic dash or a relaxing experience. Scrape slowly and not too hard!

Once that coat is partially set up, enough so the glass won't float up, add another coat of straight epoxy. Get the surface wet but not so much that it runs or sags. Those are a sanding nightmare. You shouldn't have to use the scrapper unless you get a big sag. Apply one or two more coats to fill the weave. Apply each coat when the coat below has set up just enough to not be moved around.

It takes all day to do a proper layup and a helper makes everything easier. Make lots of small batches of epoxy. If a batch starts to go off, toss it. Same with with the epoxy from the scrapeing step; it will have so much air mixed in it won't properly wet out the cloth.

I've never done it, but you could add some microballoons to that last coat. Don't add so much that the epoxy starts getting thick. You sould probably test it on a box or something first. For that matter, if you've never done epoxy work, make a tongue box or something and try it out first to get feel for how to do it.

Pmullen503 wrote:Colloidal silica is used to thicken epoxy when you want to use it as a glue you don't plan to sand. It toughens epoxy. The microballoons make it easier to sand but compromises the strength as an adhesive.

What I've always done is fair the surface and fill small dents with epoxy/microballoons mixing as much microballoons as needed to make a putty; 75% or more microballoons. This will set up much faster that epoxy alone so don't make more than you use in several minutes.

I've always applied cloth over dry wood but I'm used to compound curves on boat hulls so you really have to get the glass to lie flat before you wet it. Apply epoxy with a foam roller maybe a couple feet at a time. Keep looking back at the areas you've done and wet out any dry spots as you go.

Before the epoxy sets, scrape the excess off. This pushes the glass against the wood and dramatically reduces the need for later sanding. Depending on how fast your epoxy is this can be a frantic dash or a relaxing experience. Scrape slowly and not too hard!

Once that coat is partially set up, enough so the glass won't float up, add another coat of straight epoxy. Get the surface wet but not so much that it runs or sags. Those are a sanding nightmare. You shouldn't have to use the scrapper unless you get a big sag. Apply one or two more coats to fill the weave. Apply each coat when the coat below has set up just enough to not be moved around.

It takes all day to do a proper layup and a helper makes everything easier. Make lots of small batches of epoxy. If a batch starts to go off, toss it. Same with with the epoxy from the scrapeing step; it will have so much air mixed in it won't properly wet out the cloth.

I've never done it, but you could add some microballoons to that last coat. Don't add so much that the epoxy starts getting thick. You sould probably test it on a box or something first. For that matter, if you've never done epoxy work, make a tongue box or something and try it out first to get feel for how to do it.

This is really good advice. I would shy away from the colloidal silica unless you're worried about giving the epoxy strength (like a fileting operation). The microballoons work great for fairing an uneven surface, but the end result is porous so I always give it a final coat of straight epoxy before sanding and painting.

TCJ wrote:
This is really good advice. I would shy away from the colloidal silica unless you're worried about giving the epoxy strength (like a fileting operation). The microballoons work great for fairing an uneven surface, but the end result is porous so I always give it a final coat of straight epoxy before sanding and painting.

Porous? First I've heard of this! Please tell me more!

I just tried microsphere's and honestly don't care so much about them. I'm working vertical surfaces and need it to be more like putty. $ for $ I like corn starch better. Even going 1:1 mix it's thick and cost me maybe 25 cents (??). I used 1/8th of a quart ($1.87) for the same amount of resin and not even thick.. I can see using on the bench (horizontal), but vertical.. not so much.
Down side seems to be more clogging of sandpaper.

Only MHO under my circumstances/needs. I figure to mix in the microsphere to use it up.. then again if porous.. probably toss it.

For a fairing compound, you thicken marine epoxy — System Three, West/Gougeon, or equivalent — with glass or phenolic microballoons (West System 407, 410,or equivalent). Mix the epoxy, add the filler until it is roughly peanut butter consistency.

Apply it with a toothed spreader and then squeegee it in. Let it cure, the get out your misery whip and fair it. Repeat until you get the desired surface.

This is a misery whip:

http://sliverpaddleboards.com/paddleboa ... ing-board/



But first, get and read the literature. It's free. And feel free to call their technical support — they have a vested interest in your project succeeding.

https://www.systemthree.com/pages/modif ... -materials

https://cdn.shopify.com/s/files/1/1000/ ... _Edits.pdf

https://www.westsystem.com/instruction/ ... tion-book/

nbcarey wrote:
This is a misery whip:

paddleboard

Either way I need one! Thanks

twisted lines wrote:

nbcarey wrote:
This is a misery whip:

paddleboard

Either way I need one! Thanks

Also more formally called a longboard. Piece of 1/4 ply so it's flexy enough. Rip it to the width of a roll of stickyback sandpaper, probably 2-3/4 inches.

Fix a knob at each end, probably want to countersink the screw/bolt—if they're proud, it will score the workpiece.

Slap some sticky sandpaper on and you're ready to go.

I used the West System fairing filler on vertical surfaces and mixed it very thick... still sagged. Ended up rolling cabin onto side and using much looser mix to fill the weave.