Hull Epoxy and Paint Renovation

[Ian Bamsey]

Ok, so all the paint is off my Tiki 21. After removing the paint (not by sanding) I'm cleaning up the surface by sanding. Clearly I'm taking care not to remove much gel coat but in places this is inevitable (in a few places I can just make out some weave).

Would it be wise to paint on a new thin gel coat, or will the epoxy primer (the next coat) be doing the same job?

[kim whitmyre]

Ian, a coat of neat epoxy, and before it cures, a coat of thickened epoxy to better fill the weave.

[Robert Hughes]

I'd agree with Kim.  The only advice I'd add is to make sure both the hull and the surrounding air are warm enough for long enough, and follow the manufacturer's instructions about curing and overcoating times.

[Galway Bay]

Perhaps it is just me or my epoxy but unthickened epoxy on a vertical surface runs. I would always use some thickening agent on a vertical surface.

[kim whitmyre]

The neat epoxy can be applied in a thin coat and allowed to set up until sticky. Should be no problems with runs. Then the thickened mix is applied.

[Ian Bamsey]

Thanks for all these useful comments.

I still wondering how much gel over the cloth I might have actually removed with just a few passed of an orbital sander (80 grit). If I paint with a high build epoxy primer, will there be any difference? A thin and thick coat of epoxy first will no doubt add more than was removed. I'm only talking about above the waterline here. I've left the old antifoul on and cut that back to good paint with the sander ready for a new coat(s).

Unfortunately I have limited experience in this.

[Galway Bay]

Again perhaps just me and mine but by the time mine is sticky it has already formed runs. Perhaps try on a small piece of scrap first. Lots of things affect this but workroom temperature is a major factor.

Gougeon Bros. advice on covering is that ply is sealed with a build - up of about 200gm/m and any resin over 500gm/m adds abrasion resistance only as the ply is completely sealed by this amount. A coat of cloth takes about 500gm/m to soak out so unless you have gone mad with the sanding and removed glass cloth you are good.

Two pieces of advice I was given by a pro. contractor -

 1. Always mix a small amount of bead to any coat that you even might have to sand later. During setting it migrates to the surface and a quick light sanding breaks these beads to form a perfect base for any later layer of resin or paint.

 2. When filling, amateurs sand down, professionals build up.

Best of luck I am sure you will do a great job.

[Ian Bamsey]

Again most helpful. I don't believe I'm through to the cloth, I will have thinned the top coat a small amount. There are a few places where I need to repair some minor damage, plus a fair sized hole that needs a ply insert. In conclusion, I think only these places will need special attention and added layers of epoxy. I can put the hulls horizontal (Tiki 21).

My biggest concern now is the creeping light that slowly invades each end of the day. I have a sense of urgency - there's much to do as spring looks over my shoulder!

[Marty Peters]

Can you only see the weave or can you feel it? Depending on how rough it is I would either fill with epoxy thickened with micro balloons or a good coat or two of a high build epoxy primer.
I used lots of jotun pen guard HB primer and it fills most minor "blemishes". I applied with a spray gun and any small imperfections I just coated multiple times. The jotun I used could be over later once touch dry in around 10-15 mins so a good thickness can be built up quite quickly and it sanded like a dream to remove the orange peel and to key the surface for the topcoat. Don't put it too thick per coat or it forms a skin and the inside stays wet for ages and is terrible to sand.Sand with a 150-220 disc on a random orbital sander or about 300-400 if by hand and it should give you a great surface to put the topcoat on. If you haven't heard, the final finish is all about the prep, if you are painting on a rough surface then it's going to show through. A great paint job is 90 % prep before the topcoat goes on.
Oh and don't be afraid to experiment, you can always sand it off and start again if it doesn't work.

[Ian Bamsey]

Great advice Marty. No I can't feel the cloth. I also plan to use Jotun HB primer. This feels right. I'm interested in the spray / roller option. I've been put off spray by some people and comments, should I be?

[wakataitea]

i would not recommend to paint pure epoxy. a epoxy primer and some more layers of epoxy barrier coat will give you the best protection. epoxy is not made to be used as a paint and is not UV stable at all...

a barrier coat or primer will be although easy to paint on vertical surface...

[Marty Peters]

Personally I would spray as you will get a much smoother finish, just make sure you use lots of thinners, around 20-30% and biggish nozzle on the gun, a 2.0 is good.
Roller is ok but make sure you get solvent resistant foam rollers, I found smooth foam rollers have best finish but much more sanding compared with spray.
Now the important bit....
Any paint that contains ISO cyanides is potentially dangerous stuff and in a perfect world you should use a full covering tyvec suit with an air fed mask. The long term effects can be bad...
I did all of my spraying outside, and I was fully covered, but I couldn't find an air fed mask so after consultation with my local paint guy I bought the best mask and solvent filters they had, (about 120 usd).
I might get flamed for advising this setup but that's life. I was pretty gung ho at first and sprayed with bare arms but you soon learn that that's no good as you can feel the solvents attacking your skin. From what I understand it's the long term exposure to the Nast chemicals is what does you in. If I was going to be spraying regularly for a living I would have the full proper setup. Whatever you decide make sure it's well ventilated and wear a good mask even if you use a roller, the solvents smell real bad and if you can smell them in the mask then the filters are no good..
Hope this helps...

Marty