Thread: GIS: Epoxy coating, spar glassing, lettering questions

Hello Jeff,

1. The textured surfice is quite normal, especially if you use the wet on wet approach. After some experimentation, I find the following approach working best

Give the plywood / wood a quick sand with fine grit sandpaper (240) after which you apply the first coat of epoxy. When the epoxy has cured, I wash the surface with a water/vinigar solution to get rid of any amineblush and sand the epoxy with fairly rough paper (grit 80) to make it all flat again (the epoxy raises the woodgrain). Than I put on another 2 layers of epoxy wet on wet. Before sanding, I wash the epoxy coated area once more with a water/vinigar solution. Than some sending with 120 and later 240 grit sandpaper and one more wash down to remove any epoxy dust. I am sure there are faster methods, but this one makes sure that the surface will be very smooth and well coated before applying any paint or varnish.

2. When I built the square mast for my GIS, I asked MIK the same question. I have put 2 layers of light glass around the bottom end (first 100 cm) of my mast to prevent any splitting. If I recall correctly, MIK has later advised that some glass or glass tape at mastpartner level only shoud be sufficient. But I let MIK confirm that.

I have not glassed the ends of the boom and yard (MIK advises glassing of the ends where you drill the holes). The hailyard however does go around the yard to prevent it from splitting (recommended in MIK's extensive rigging instructions on his website).

3. This might work. I know that people apply the same method when varnishing.But you need some thickness to prevent any damage to the letters when sanding.

Hope this helps.

Regards, Joost

Joost almost had it on #1. You want to roll and TIP the epoxy on. You are missing the "tip" part, I think. The only other possibility -- and I hope it is not the case -- is that the second coat of epoxy orange peeled because of amine blush on the undercoat. But you say you hot-coated, or did wet-on-wet. Did you tip? That means, roll on the epoxy and gently drag a foam brush (or a roller cover cut in half to make a half moon shape) across the coat to smooth out the bubbles and stipples. What the texture looks like to me is the stipple pattern made by a roller, so I would say you are rolling, but not tipping. You can brush and tip too...I'll brush against the grain and then tip with the grain. Always tip with the grain. Every other coat sand it with a hard block and 180-220 grit sandpaper so that the surface is uniformly dull which tells you it is flat sanded. Clean well and roll and tip another couple coats on.

#2 - I built a rectangular-hollow mast for Dana who is here on the forum. I think MIK recommends glassing from the butt end of the mast up 1200mm. I felt that this was way farther than necessary. The idea is to give the mast some abrasion resistance from stepping and unstepping. So you only need to go a little ways past the height of the partner.

It is a REALLLY good idea to glass the ends of the spars to prevent splitting especially wityh 9+mm holes in the ends! Joosts will probably split, especially the way he is using the boat which is the way it should be used -- HARD!

#3 That is a good idea...go right over some lettering. You can also wait and varnish over the lettering. That may be a good idea if someone else were to buy the boat and rename it.

Cheers,
Clint

Hi Jeff,

Sorry about that and thanks for putting the pic and your questions up.

Surface finish
I find the best way to get the epoxy flat is to do all the coats wet on wet, use a roller like normal. When you finish the coat hold the roller in your gloved hand so it cannot turn and slide it across the surface with light pressure. It will pop all the bubbles and get rid of the roller texture.



The above is the raw epoxy finish using the sliding roller method. If you look closely you can see some defects but they are not deep.

Wet on wet is really important because there is always the chance that if you stop then something can go wrong with the following coats because of the aminebloom/wax problem. I always go through wet on wet - allowing the previous coat to get tacky. Dewax at the end (if necessary) and sand and it is done. Only one lot of sanding and only one chance for amine.

I would usually go to three coats of epoxy as even this rough surface could probably be sanded down without breaking through to the wood. The idea is not to reach perfection as you can do that with the paint or varnish later, but to minimise sanding - so hopefully this method helps.

Glass tape on spars
Correct - you only need some tape around the partner area of the mast and the ends of all spars. The longer piece of glassing is not necessary - we built some masts without the long piece and they are fine.



Again ... this is not a separate process. When you put the first coat on the whole of the spar - use the sliding roller method to make it smooth then put the glass tape on the ends and the partner area of the mast. Then when you do the follow up coats wet on wet it will fill the weave of the tape. Good place for peel ply if you want to try it too. Just over the taped areas - not the whole spar!!!

Your web site
Cool ... we want the link ... please add it to your signature or refer to it as much as you like. Often you can use the same images in posts here just by using their URL

Lettering
I know surfboard people print things on rice paper and it disappears when the resin goes over. I would do a test. Or you can see here ...
http://www.pdracer.info/PDRbuilding/...sandsigns.html

Looks like I have a little more editing of the GIS plans to do .. thanks again for pointing this out Jeff.

MIK

Thanks for the responses, guys. Lots of good stuff to respond to so here I go.

Regarding the epoxy finish:
- Joost, your technique sounds like a good one. I may give it a try... however...
- From what MIK says, it sounds like I don't need to get a nice smooth finish on the epoxy; just as long as I get a nice smooth surface in preparation for the varnish, I should be good. Makes sense, but I hadn't thought about it that way. This makes me feel much better.
- MIK & Clint: I'm using the Bote Cote epoxy, so amine blush should not be a problem (at least, that's my understanding). I have been tipping/dragging the foam roller (making sure it doesn't move) to get rid of the bubbles, and that's been working well. I have also been doing it wet-on-wet, which saves on the sanding between coats, but it takes almost four hours to get tacky. I don't know how much this varies from others' experience, but I suspect the climate here affects the cure time the most.

Regarding glassing the spars:
- Will glass the mast near the partner and the ends of all the spars. Thanks for clearing that up for me!

Regarding lettering:
- I think I'll hold off on the lettering until I'm ready to varnish. I suspect I might have a bit of difficulty keeping the letters in place while dragging the roller across the surface to get rid of bubbles.
- I did see that PD Racer page, but I just bought a skookum new photo printer and thought I could put it to good use..

Regarding my web site: Sorry, I thought I made links out of the text in my postscript. If that didn't work, here are the URLs:

My web site is at http://www.jeffisaak.com
To view my GIS posts, visit http://www.jeffisaak.com/viewBlog.do?cat=10
My build photos are at http://www.jeffisaak.com/gallery.do?blog=1&gallery=025!Goat_Island_Skiff (yes, the URL is kind of gross)

Jeff

Yes Clint, I missed writing up that part: I normally roll on the epoxy but tip it using a wide brush. Works a treat but costs another brush compared to tipping with the roller.

And if not using the wet on wet method for all three coats, it is very very important to clean the surface thoroughly both before and after sanding to get rid of any amine blush that might prevent the epoxy from sticking well.

Good luck Jeff!

Epoxy is wonderful stuff but it ain't paint and it ain't varnish. Paint and varnish are engineered to be self-leveling and to resist runs and sags--epoxy isn't and it can have both as well as the orange peel effect you got. Count your blessings that you aren't dealing with the runs and sags I got on mine!

I see from your blog that you ordered the sail from Dabbler. I think you made a very good choice, there. If possible try to have the boom and yard finished when he starts on your sail. He will give you detailed instructions for measuring and recording the amount of flex in YOUR spars so the proper amount of draft can be sewn in. Without those numbers he would have to use MIK's instructions (to figure about 2" of bend) or perhaps use the bending numbers from mine, which, BTW, were just about what MIK predicted.