Epoxy Questions

[SWA]

After putting the fiberglass and first layer of epoxy on my boat, I found numerous air bubbles caught underneath the fiberglass on the edge. I have since ground them down and opened them up. My question is since they are on the edges, and gravity will come into play is there a thickener that will still allow for a possible future bright finish? I have also found numerous whiteheads where the dust from sanding has filled small craters in the finish. How do you deal with these? Finally, I have heard several people talk about using a squegee (most likely mis-spelled) to apply the epoxy and that it gives a much nicer (less sanding) finish. Can someone tell me how well this works and what type of squegee they use. Thanks!

Steve

[mhoffman]

Steve-
yes the squeegee is a good thing- at least for the initial wetting out of the cloth. They are medium density plastic and are reusable. Check with you epoxy supplier. It really helps with wetting out your cloth better and forcing air bubbles out in the first place.
I would recommend a light sanding (very) just enough to abrade the surface and knock off any dust bits, but not cut in to the cloth before the next coat. Wipe down with water- if you have an epoxy that blushes, or it been a few days, use mild detergent first, then wipe with water to remove the film.
For the craters, try unthickened epoxy if you are finishing bright- small paintbrush, a couple of coats, should do it. Best to avoid the craters in the first place though... The squeegee should help.
For subsequent coats of epoxy to fill in the weave and finish fairing out, I used the small foam rollers- the white ones for varinishing work pretty good. Some brands tend to drop little bits in you epoxy- those come off easily enough with a razor before the epoxy fully cures.
The biggest thing if you are finishing bright is not to sand into the cloth- the weave will show up if you are close. You might be able to fix it if you do sand too far by wiping the area down with denatured alcohol and recoating.
Remember the five foot rule though- if you can't see it at five feet, its not important.

Keep at it!
Matt

[edsr]

Something that I have noticed when using glass and epoxy is that when you have a good bond it becomes transparent. On new wood it looks likes varnish, any whitish areas will definately become pockets after the stuff cures. Anywhere there is a fold or sharp bend you can observe this "look". Squeegees work very well to move epoxy around. They are the favorite tools for large jobs. Cheap bristle brushes are fine for smaller tings. You can get squeegees in the auto dept. of hardware/variety stores, they are used for auto body repairs.

A very important point, when you work the epoxy be careful not to overwork it, it get filled with tiny air bubbles and looks almost creamy, that is a bad thing. It should look like clear, transparent syrup.

Be sure as mentioned above to wash with detergent and water and wipe, changing the paper towels or rags or whatever to remove amine blush especailly if the first coat has cured too long, usually more than a day or two, check the mfg. recommendations.

If the voids are relatively small and not structural you can thicken some epoxy with silica, baloons, etc. and make an invisible patch.

Hope this helps.

edsr

[capt jake]

The squegees that I use are teh ones sold at autobody shops for applying Bondo. They work great, but as has already been siad, don't overwork the epoxy.

The air bubbles can come from several things. teh first one that comes to mind (been there done that) is if you left any small 'holes' in the wood prior to applying the epoxy. I had the same problem with a stripper kayak held together with staples. I missed filling a couple of the staple holes, and this created bubles over these minute holes after epoxy application.

Try to fill with unthickened epoxy if you are going for a bright finish. Fillers will obscure the look.
Good luck. smile.gif

[Bruce Hooke]

One technique I've heard about but never tried for filling holes when the finish will be clear is to use unthickened epoxy and then put a little piece of Saran Wrap or tape over the epoxy until it cures. I think this was from the Gougeon Brothers book so you might look there for more details. (I can't imagine doing any serious epoxy work without having that book on hand as a reference.)

[edsr]

If you are looking for a glass smooth finish the plastic wrap realy works, if you can put some pressure on the edges of the plastic. Taping a patched area on all edges will do it. Usually an orbital sander and working through the grits with a final wet sanding #600 > #2000 will produce all the smoothness most people need. Oh, one other thought about bubbles apearing is to dry out the area being glassed. A few small cheap electric space heaters work well. Reducing the internal moisture will also reduce the bubbles. Let the project cool or the epoxy will kick to soon.

edsr

[JimD]

Originally posted by SWA:
After putting the fiberglass and first layer of epoxy on my boat, I found numerous air bubbles caught underneath the fiberglass on the edge. I have since ground them down and opened them up.

My question is since they are on the edges, and gravity will come into play is there a thickener that will still allow for a possible future bright finish?

SWA, no, there are no thickeners that cure clear so do the best you can with unthickened epoxy.

I have also found numerous whiteheads where the dust from sanding has filled small craters in the finish. How do you deal with these?

Brush, vacuum, or wash them free of the white dust and recoat with epoxy. They will be virtually unnoticable after an epoxy recoat. Clear uv blocking top coats like polyurethane will also fill them in clear. Washing between epoxy coats is always a good idea to make sure you remove any blush film

Finally, I have heard several people talk about using a squegee (most likely mis-spelled) to apply the epoxy and that it gives a much nicer (less sanding) finish. Can someone tell me how well this works and what type of squegee they use.

I always use a squeegee (also most likely mispelled) to spread the epoxy on both bare wood and fiberglass cloth, and then use well gloved hands to work out the irksome little bubbles and squeegee lines that sometimes occur. Use a flexible plastic squeegee. Well equipped epoxy suppliers all have them. You can try a hard plastic squeegee such as are used for drywall mud but they won't do nearly as good a job and tend to snag the cloth or scratch the wood

Thanks!

You're welcome smile.gif

Steve

[Dave 901EM]

SWA,
Rob White said in an article for WB a few years back that you should never (among other things)glue/glass/varnish in a heating shop. He would jam the temp of his shop up to 120 degrees then shut the heat off and start gluing. Instead of taking his word for it I did a big layup as the temp was on its way to 75. (shouldda known better, Cap'n White has been doing this longer than me..) BAD IDEA! Lots of little bubbles and whiteheads. Close examination of the whiteheads was zillions of micro bubbles around the "big" bubble. Whole thing smaller then 1/32 inch. The little bubbles were worse where the cloth was not really saturated to the point of almost floating in the epoxy, it was easy to see that the wood sucked in a bunch and the little surface blivets would produce a bubble. Where the epoxy was thicker, there were more whiteheads.
The thing that got rid of the zits and bubbles was a scraper. Cap'n White also did a piece on using cabinet scrapers to clean drips, and other oopses like bubbles up. If you don't have these, you can get them from Woodcraft for $12 plus shipping and they will change your life. I now don't have nightmares any more, the scrapers were the best tool that Santa Clause brought me. I did the old saw blade routine but too much time was needed to polish the blade pieces.
As for the filling of the edge bubbles, SMALL amounts of fumed silica will stiffen up (can't spell thixotropic) the epoxy BUT!!!!, if applied to thickly, will show up cloudy/white. Good luck and get those scrapers!

[Captain Pre-Capsize]

This whole thread just reaffirms my decision to take the path of least resistance and paint the outside of my boat! tongue.gif

(Guess I violated my quote - see below!)

[ 04-18-2003, 09:00 PM: Message edited by: Captain Pre-Capsize ]

[JFH]

I've chased epoxy with a heatgun once I applied it and it just got sucked into the pours of the wood that I applied it to. You're right about cap'n White,...he is the man when it comes to epoxy. Found a post here somewhere about his unorthadox techniques. Just do a search and ye shall see the light and ....less drips and bubbles.