Flowcoat

Can polyester flowcoat be applied over epoxy laminate or am I better off mixing some pigment into the epoxy for a sealing coat?

 

No, the bond will be poor, mixing pigment in to epoxy helps a little, but its not sufficient to stop UV degradation. Use a paint, it will be low in cost and work very well.


But then it also depends what you plan to use this item for.

 

May I add (and correct a little):

pigment helps NOT, the EP will still deteriorate under UV at the surface.

Instead of paint, UV protecting varnish can be used as well. And that must not be the expensive PU stuff.

As mentioned, much depends.........

Regards
Richard

 

Actually pigment does help a little. The UV rays are blocked before they can penetrate deeply into the surface when high pigment concentrations are used. This means degradation of the surface will still takes place, but the epoxy below the surface is affected less than it would be without pigment, so it can take longer for it to breakdown.

This is not a good solution, but it does "help a little".

 

Well, yes, a little.
But neither you, nor me would recommend it! After a while it would make trouble due to further degradation.

 

The application is for a locker under the cockpit floor so uv not an issue. My main concern was the bonding of the two differen't types of resin, sounds like it won't be good so I will use the pigment or paint option, only thought of flowcoat as I have some available.

 

The bonding will not happen! (or at least not sufficient)

The pigment option was already handled by both of us! Leave it.
Apart from UV degradation any unproven "filler" can change the desired properties of your expensive epoxy layup. So, do´nt risk that, paint it with some exterior house paint!

Yes, that was meant seriously, ext. house paint on EP, that is usually sufficient for your application.

And, it might be impressive to discover, how much light (incl. UV) one can find beneath a cockpit floor. I once had a architectural drawing stowed in a drawer with a ventilation grille, the cabinet was not far from a tiny, transparent solar vent of about 3 in. diameter. After about 2 years the front page was almost plain yellow due to UV light!

Good luck
Richard

 

if the epoxy is sanded with 80 grit would this provide enough of a key for the gelcoat? I was thinking of using gelcoat/flocoat in my epoxy/ply/glass anchor locker. I know polyester wont stick to epoxy chemically but what about the mechanical bond? has anyone tried this?

 

It still is a poor bond and prone to failure.

Regards
Richard

 

I used this over the new epoxy in my engine compartment. I was very pleased with the results.....

http://www.yachtpaint.com/usa/diy/products/finishes/bilgekote.aspx

MIA

 

I don't know anything about this stuff it looks like it might be good. Googled "epoxy gelcoat". This is a polyester formulation designed for use on epoxy substrates-from the UK. Anyone know anything about it?
There are a few other companies...

http://www.scottbader.com/downloads...nding Polyester Gelcoats Brochure_English.pdf

 

I would recommend an epoxy coating of some sort. If you were to knock on my door I would give you a set of ecoProtect from ecoLine Coatings, but there are many more.

Epoxy compatible gelcoat does not work. It only works the other way round.

However, there are some types of epoxy that do allow polyester topcoat over it, with enough adhesion to survive. Ideal for repairs.

 

Put simply DONT MIX RESIN TYPES !!