epoxy blister repair question

[AndyEss]

Originally Posted by ferrailleur

Correct I'm kind of impatient... The boat has been on the hard for six months with soda blasting and me grinding blisters hours and hours.... rinsing and rinsing and "acetoning" the cavities....
Now I'm brushing non hardened 105/205 West System epoxy... and filled the cavities with hardened epoxy.....
I know that some blisters will return next year at haul out.....
But so what? If it's only 5-10% ???

Non-hardened epoxy?
I guess that might help it soak into unwetted glass (if present) but it sounds like a good way to have a weak bond layer for the thickened and hardened filler coat.
Possibly a better route would be to work with a lower viscosity, extended cure first, "penetrating" coat.

[Franziska]

Originally Posted by timeout2

Yes, it is a long process with a LOT of sanding. You can use West 105 as a barrier coat. Each coat must be washed and lightly sanded before next coat.

Sorry, I'd like to kindly disagree with the sanding in between coats, if he uses a hardener with a long enough open time he should be able to coat directly over towards the end of the green stage.
West will be able to advise on the max and minimum time-frame to do so.

A chemical bond between coats is always better than a pure mechanical one. This is especially true when you are not doing it very often or very diligently. Because if you rely purely on sanding you always run the risk to have some areas with bad adhesion due to dust entrapments.

In any case I'd advise to do as much fairing once all former bubbles are filled. Use a proper epoxy fairing compound to do this.
This way you avoid thinning the barrier coats down by to much sanding.

Once everything is nice and fair apply your barrier coats in the proper timing (as above).

Ideally you should use alternating colors for each barrier coat. That way you avoid sanding through them.

Good luck & lots of success!

[ferrailleur]

Originally Posted by chowdan

Being impatient is fine, but atleast focus on doing the job right.

It's no point to do the work and do it wrong when you'll have to go back and do it all over again because the "fix" you did failed.

That's something I've learned over the years working on my boats, working as an engineer. If your going to do something, do it right once, and be done with it or dont do it at all. It will only waste time and in turn money

Thanks.... I'm learning to tame my impatience...
I appreciate your over the years experience
Now: I'm finished grinding (hours + hours). I have rinsing/acetoning/drying ….
I'm in the stage of filling before epoxy barrier coating before paint.

[ferrailleur]

Originally Posted by AndyEss

Non-hardened epoxy?
I guess that might help it soak into unwetted glass (if present) but it sounds like a good way to have a weak bond layer for the thickened and hardened filler coat.
Possibly a better route would be to work with a lower viscosity, extended cure first, "penetrating" coat.

Sorry for the confusion. I was brushing 105 + 205 (hardened epoxy) on the clean raw fiberglass and then filled up with 105 + 205 + colloidal (406)….

I did that on one side of the hull.

Better suggestion for the other side?
Thanks

[Franziska]

Sounds right to me. If you have deep blisters, sand, clean & add a few layers of glass.
Then fair it thoroughly, remove any dust. Make sure everything is sanded and clean.
Than put your barrier coats on as described above.
Once they have cured, sand lightly, remove dust all over and put underwater paint on.

[Franziska]

Always make sure your hardener to resin ratio is 100% correct. Epoxy needs this and is not forgiving on this as polyester is. Get it wrong and it will not cure.

Check if the ratio is given by volume or weight.
If mixed wrong, discard batch and mix anew.