Roach1948
Well-Known Member
Can I use polyester resin over epoxy? For one reason and another I have run out of epoxy and the only thing I can get hold of is polyester resin. It is not being used to bond, just to coat/seal the inside of a dinghy.
Resins - can I combine the two?
- Thread starter Roach1948
- Start date
Rum_Pirate
Well-Known Member
My guess is absolutely not.
No doubt there will be a knowledgeable person that will make me eat humble pie.
No doubt there will be a knowledgeable person that will make me eat humble pie.
Peterduck
Well-Known Member
Rum Pirate is quite correct. Polyester resin is useful on plastic boats and dented cars, but not on wooden boats. One problem is that it doesn't stick well, and another is that it is permeable, so it won't act as a sealer. Strangely, a good sealer is a few coats of Shellac. It does need a coating of good oil-based varnish over it to protect it from UV light and abrasion. A better sealer for out-of-sight places is Red Lead paint (dilute the first coat a bit).
Peter.
Peter.
Roach1948
Well-Known Member
OK - what shall I do now?
This is for sealing the high abrasion areas such as sole, sides and thwarts of a stitch'n'glue ply new build. Not in a place where I can get epoxy or ANY fancy marine coatings.
So what shall I do? Red Lead I can get hold of. Alu Oxide too. but enamels will be traditional exterior house paint. What are my options? Start building up traditional paint layers?
Pen Duick - Never heard of Shellac; Could you suggest ingredients be to make a home-made alternative?
This is for sealing the high abrasion areas such as sole, sides and thwarts of a stitch'n'glue ply new build. Not in a place where I can get epoxy or ANY fancy marine coatings.
So what shall I do? Red Lead I can get hold of. Alu Oxide too. but enamels will be traditional exterior house paint. What are my options? Start building up traditional paint layers?
Pen Duick - Never heard of Shellac; Could you suggest ingredients be to make a home-made alternative?
DownWest
Well-Known Member
As you are out in the wilds with no access, some thoughts. A member of the Dinghy Cruising ass. built a ply boat in the 70s and coated it with polyester as epoxy was new and expensive (ok, I know it has been around since the 40's, but not for amateurs) His boat is still fine and much used.
So, how long do you want it to last? The Mirrors were polyester taped and many are around.
Lots of people use house paint on their boats. It is important to protect the epoxy from sunlight. But I coated the whole boat in epoxy and two years on am only just getting round to paint and varnish. It is stored inside so exposure is low.
Use what you can get.
Iain Oughtred tells of a boat built to his plans that had no coating at all for some years, just bare ply.
Andrew
So, how long do you want it to last? The Mirrors were polyester taped and many are around.
Lots of people use house paint on their boats. It is important to protect the epoxy from sunlight. But I coated the whole boat in epoxy and two years on am only just getting round to paint and varnish. It is stored inside so exposure is low.
Use what you can get.
Iain Oughtred tells of a boat built to his plans that had no coating at all for some years, just bare ply.
Andrew
burgundyben
Well-Known Member
I reckon so.
I'd tend to agree with our Rum drinking friend if it was your boat, but as its a ply dinghy I reckon it would be fine and add a few coats of paint will do the job just fine.
I'd tend to agree with our Rum drinking friend if it was your boat, but as its a ply dinghy I reckon it would be fine and add a few coats of paint will do the job just fine.
Peterduck
Well-Known Member
Shellac is a secretion of the lac beetle which lives in India. It has been used as a coating for timber since Vasco Pajamas brought some back with him in 14-something. This was the principal coating used for French Polish on fine furniture. It is still available, either as a liquid or as flakes to be broken down by methylated spirit. I would buy it from my local paint shop here, but I don't know where you'd get it near you.
Peter.
Peter.
beachbum
Well-Known Member
If I read it right, the question was not polyester-on-wood but polyester-on-epoxy, some epoxy already having been used. To that I believe the answer is no: I'm no chemist, but I always understood the rule of thumb is epoxy sticks to anything, nothing sticks to epoxy.
dur
Well-Known Member
I would go for the traditional exterior paint: primer, several undercoats until it looks right and then a couple of top coats. Just give it as long as possible to harden before using.
laurance
Well-Known Member
If your epoxy is cured, well keyed-up then properly cleaned you can chuck on as much polyester as you like. Polyester used like this is merely more permeable than epoxy - GRP boats don't leak through their laminates now do they, they just get a bit soggy. As has been said UV protection in the form of a good varnish or paint is important.
Roach1948
Well-Known Member
So what now?
The plans call for the whole boat to be sealed in Epoxy (the outside already done). So do I:
1. Polyester coat the sole, thwarts and remaining areas etc. after keying the epoxy taped seems well and paint over as per usual.....or
2. Red lead primer, then paint build up, forgeting about using anymore resins.
3. Find and start squeezing a lot of beetles....
The plans call for the whole boat to be sealed in Epoxy (the outside already done). So do I:
1. Polyester coat the sole, thwarts and remaining areas etc. after keying the epoxy taped seems well and paint over as per usual.....or
2. Red lead primer, then paint build up, forgeting about using anymore resins.
3. Find and start squeezing a lot of beetles....
DownWest
Well-Known Member
No 3 if you are in Egypt and it turns you on....
As it is internal only (you still have to coat the outside to protect the pox ), primer and lots of coats of good house paint.
The aluminium stuff is popular in 3rd world areas so should be a good base coat. The ally is a good UV block. ( used on fabric aircraft)
About things not sticking to epoxy, it has to be covered because of UV, not a big problem with polyester, so when it is cured a good keying and any thing will stick. It is a mechanical bond, not chemical.
A
Sorry, India not Egypt
As it is internal only (you still have to coat the outside to protect the pox ), primer and lots of coats of good house paint.
The aluminium stuff is popular in 3rd world areas so should be a good base coat. The ally is a good UV block. ( used on fabric aircraft)
About things not sticking to epoxy, it has to be covered because of UV, not a big problem with polyester, so when it is cured a good keying and any thing will stick. It is a mechanical bond, not chemical.
A
Sorry, India not Egypt
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Sequoiah1
Well-Known Member
You will need a primer that wil stick to the epoxied seams internally(sure you will find something a t DIY store), use a domestic external bare wood primer and then paint with whatever you wanted to paint with. The epoxy on the outside will need treating the same as the seams inside.
MikeBz
Well-Known Member
And only slightly more recently to make records (those funny black flat circular things with a groove in them, which one tends not to see any more)...
Mike
TimBob1989
Well-Known Member
Not sure where exactly you are, but can't you get some epoxy delivered off the net? There isn't a decent-sized (and priced) chandlery here so I order everything from purple...
