epoxy dimples

I have just applied the 4th coat of epoxy to my Petrel. I have wet sanded to 220 between coats and rinsed and dried before reapplying. For the most part, the weave is covered, except the keel, where I used 6" tape and still have some filling to do. With each coat, I see progress, but I keep getting dimples in the epoxy. Any hints or suggestions would be much appreciated.


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RE: epoxy dimples

First of all, sanding to 220 between coats of epoxy is extreme overkill. The most you have to do is to take down the major drips and runs before the next coat. If you apply coats within 24 hours you really don't need to sand at all. If you want to sand between coats 150 will suffice. When you're entirely done with build up then you should sand the final coat to 220 for varnish or paint.

The "dimples", also known as fish eyes, are caused by dust, micro-particles actually, that you haven't gotten completely off after sanding. You could also run into a slight adhesion problem sanding to 220. The epoxy will bond better to a slightly irregular surface, i.e., 150 or even 80 grit sanding. I know there will be some here who disagree but I found that running my hands over the area to be epoxied after water rinsing and drying will pick up any particles left. Just make sure your hands are clean and wipe them on a lint free cloth between swipes. Unless you're an extremely greasy person there's not enough oil in your palms to cause adhesion problems. The one thing you absolutely do not want to do is use a tack cloth that will leave a residue of any sort.

George K

RE: epoxy dimples


Damn, I thought the tack cloth was the way to go, and have been using it the entire time ! OK I will not use it on the next coat. I am getting impatient and have already had the yak in 4 times. I really want to get the varnish on to get the UV protection. I bought Interlux Perfection Varnish on a recomendation from a local builder, have you used it, any advice ? I hope to attend The Wooden Boat Show in Mystic next weekend, and will try and aquire as much info as I can from experienced builders.

Will sanding and rinsing remove any tach cloth residue ? I need the cycle to end, the season is too short!

Thanks again

RE: epoxy dimples

You asked about removing the residue from the tack cloth.  I defer to those with experience in the specific question you ask.  But absent any better information, I would do this: rub off the waxy residue from the tack cloth with something that dissolves wax, not with water, which is simply repelled by wax.

I'd use acetone, or at least ethanol (sold as "denatured alcohol").  Methyl ethyl ketone would be even better than either at attacking wax, I think, but I tend to avoid it, myself, maybe just superstitious.  If I use it, I use it outdoors with a mask with activated carbon cartridges.

Detergent solution might work too, and would at least be way better than water and sanding, which I would think would just smear the wax around.

RE: epoxy dimples

Norton makes a red micro-fiber based tack rag without the “tacky” coating. I have found it works very well and can be washed out by hand and dried. You could also dampen a lint free rag with denatured alcohol and give a light wipe before coating.

RE: epoxy dimples

Any of the above mentioned solvents should remove the residue from the tack rag. I'd try the denatured alcohol first as it's probably the most benign of the lot.

As far as the Interlux varnish, I've never used it, I use Epiphanes, but I have used Interlux paints and I'm sure their varnish is as good a product.

Looking forward to seeing some pix when you're done.

George K

RE: epoxy dimples

Speaking as a professional with 30+ years in the design, manufacturer and use of tack cloth, I'd like to clarify a couple of points here.

A good design and quality of tack cloth should not leave a residue.  Retail is a poor place to find one, and I'd recommend a good, commercial grade auto supply store that deals in paint as one option.  Otherwise, find an online wholesaler that specializes in commercial quality tack cloths - discuss with them if you have questions.

There are many different designs and qualities of tack cloth -- both in the tack chemistries and textile cloth types.

Tack cloth remains the preparation of choice in many "Class A" finishing applications like much of auto assembly painting.  It is a proven way to remove dust, dirt and lint, and you can see the resulting dirt removed even after good vaccuuming and solvent wiping.  Do not sweep or blow-off, as that only distributes dirt into the air from where it will resettle on your work piece.

Microfiber wipes can also vary widely in quality and are prone to leave lint, so be careful with those, as well.

RE: epoxy dimples


Have you ever used any tack cloths for prepping a boat for another coat of epoxy? If so, can you recommend one that'll work?

George K


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