Hardener Needed for Painting Over Epoxy.

[Jim@sea]

The first time I painted a boat hull with 2 pack epoxy paint was in 1982 when I had bought a 1973 boat with osmosis.
At that time International Paints had not even started marketing Two Pack paint but I had been using the ICI Two Pack Paint (called 2K) since 1975, in my Bodyshop, so when I bought the boat with osmosis and found that the osmosis had been treated with single pack paint 3 years before, and the osmosis had come through again it seemed logical to use the two pack paint I was familiar with. (and 3 years later it had not come back)
So leaping forward to 2006 I had bought a French boat which was 20 years old and the hull was absolutely perfect. But as a painter (probably painted over 100 vans with a brush) I decided to paint the hull below the waterline with 2 Pack Epoxy. Due to a mistake in ordering I ended up with 2 pack Acrillic paint which I have never used.
So now after using Bodyshop type two pack epoxy below the waterline on my present boat (8 coats as I like doing it) I cant just put antifouling on as I need to seal the epoxy.
So I realised that I still had 3 liters of Tetrosyl 2k two pack acrillic (from 2006) which is ideal for painting over the epoxy. But I have no hardener. Tetrosyl dont make the paint anymore so I cant get any matching hardner.
So my question is, can I use any make of hardener as long as it is a two pack hardener as it would be a shame to bin these 3 liters of paint.

 

[lw395]

Are you sure that the paint you've put on is epoxy?
There are lots of flavours of 2 pack paint, epoxy, acryllic and polyurethane spring to mind.
It's quite normal to paint antifoul over epoxy.
But then again, there are many sorts of epoxy...

There are two issues, getting a hardener with the right ingredient and getting the amount right. I think it would be dodgy to chance either.
The cost of 3l of new paint is probably not so bad as the prospect of scraping off a sticky mess?

 

[Jim@sea]

Are you sure that the paint you've put on is epoxy?
There are lots of flavours of 2 pack paint, epoxy, acryllic and polyurethane spring to mind.
It's quite normal to paint antifoul over epoxy.
But then again, there are many sorts of epoxy...

There are two issues, getting a hardener with the right ingredient and getting the amount right. I think it would be dodgy to chance either.
The cost of 3l of new paint is probably not so bad as the prospect of scraping off a sticky mess?

The label on the tin says LECHSYS Epoxy Primer. I would probably mix a small amount and paint something. I will know within half an hour if the mix is good. I imagine that it dosent matter whose paint you use they all buy in their isocinate hardener from the same source, although I dont know if it is the same hardener for epoxy and acrylic two pack.
It was only because the Lechsys Paint rep was at the motor factors when I was buying some "Clear over Base" 2 Pack to use as a varnish that I was able to question him in detail

 

[Lakesailor]

9 year old paint without the correct hardner. What chance is there of that working?
I just sprayed some 12 year-old cellulose primer with some new thinners. But that's easy. Cellulose is cellulose.

Google says http://www.express-paints.co.uk/lechsys-29370-epoxy-primer-hardner-1-0l/

Depends on the code on your primer by the looks of it.

 

[William_H]

Epoxy is a materiall plastic which is created by mixing 2 components which together form the long chain matrix of molecules. If either component has too much compared to the other component then you get non linked molecules in the final plastic. Hence loss of strength and in effect a part not hardened. So as said correct type and quantity of hardener is vital.
I don't know much about polyurethane except that I have the impression more hardener can make the paint thinner for application and is OK so I think quantity is not so critical. Possibly hardener is similar for all polyurethane paints. They are my preference for touch up and deck due to toughness and UV resistance.
I have not heard of 2 pack acrylic paint.
I understood that you simply paint a/f over epoxy after scrubbing it and roughing it up a bit. May be wrong. good luck olewill.

 

[macd]

I imagine that it dosent matter whose paint you use they all buy in their isocinate hardener from the same source.

I'm no chemist, but always understood that the most common hardeners for epoxies were amines (hence 'amine blush'), although there are other classes, including phenols and anhydrides. As lw395 suggests, there a many different epoxy chemistries: it's not as simple as you seem to imagine.

 

[simonfraser]

Can you over paint a sticky mess ?
If not, put it in the bin.

 

[Keith 66]

Two pack Polyurethane is similar to two pack Acrylic in that both use an Isocyanate hardener, The Acrylic 2pack activators come in different versions to allow for oven bake or outside or winter work. I have seen quite a few yachts round here resprayed with Acrylic 2 pack, the sprayers like it as its easier to lay it on quicker.
Two pack Epoxy doesnt use Isocyanate hardener as far as i am aware. If you use the wrong stuff the chances of a poor or non existent cure are high.
Speaking from experience here as years ago i fitted a new rudder & skeg to a yacht, Owner wanted it epoxied so i used some two pack epoxy pitch i had kicking around that was long out of date. It didnt cure & it took 3 gallons of gunwash & scraping to get the filthy stuff off before i could redo it.