Problem with flowcoat not drying

[knockabout]

using epoxy flow coat at the moment it's 3parts resin to 1 part hardener. did have a layer of flow coat stay tacky last year on the main hatch slide it was the last small mix out of the tin / the catalyst may go off if old / I mixed a new batch using new catalyst and re-coated the slide straight over the still tacky flow coat it dried solid in 2 hours and hasn't been a problem / I sat the hatch slide in the sun to use the heat to help it cure // perhaps mix a small batch and over coat your stuff up in an easy to access area and wait and see if it cures o.k / if so over coat the lot / if you are using polyester flow coat try the same / take care not to breathe in the fumes for too long / epoxy goes over polyester o.k but you need to sand the lot first to key the next coat in / polyester sticks to epoxy quite well, it still pays to sand the properly cured epoxy before coating / I have cleaned up a failed hull repair on someones boat using petrol sanded it rough and repaired with 180 epoxy and q-cell mixed thick straight onto the polyester hull, shattered star crack / the tide came in and the yacht floated and didn't leak / but that was in an emergency with makeshift repair materials .

[smj]

Originally Posted by amoret

I should clarify...It's the flow coat laid over the epoxy that won't dry. From comments above I suspect the problem is that amine blush wasn't properly removed from the epoxy. The amine blush has contaminated the flow coat preventing it drying/hardening.
The other area that was flowcoated has worked very well because it was not laid over fresh epoxy. The same mix ratios and procedures were used for both jobs. The catalyst used with flow coat is called MEKP and 1-2 % is recommended. I thoroughly 10 ml into 500ml of Flow coat (2 %).
It's interesting that the Flow coat won't dry due to Amine blush as Flowcoat is just Gelcoat with a wax added to it.
Thanks for all the input, sounds like it aint gonna dry. Looking like a messy clean up ahead.

So you used polyester over epoxy?


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[elbib]

Your not the first person to have this problem, the cause is probably the use of polyester laminating resin over any substrate. That resin is designed to be used in a mold or any airtight system such as a vacuum cure.

The simple cure for your problem now is to coat with epoxy, sand if necessary, then you can finish with an epoxy primer and paint.

Laminating resin is designed that way so that it does not need sanding from one layer to the next. The last layer will have to be a finishing resin, finishing resin has a wax or something similar mixed into the resin that rises to the surface during the cure, therefore restricting the air.

Lew on S/V Allusion

[amoret]

Yep , Flocote is a polyester resin with thixotropic ingredients and wax styrene. Tried to put it over West epoxy resin. Nothing that a scraper, old towels and a bucket full of acetone couldn't fix. Used mask, gloves etc as it was very confined, awkward space.
Thanks for all the input and advice.
Lesson learnt!!

[knockabout]

yes polyester flow coat isn't as forgiving as epoxy flow coat

[valhalla360]

Originally Posted by amoret

Yep , Flocote is a polyester resin with thixotropic ingredients and wax styrene. Tried to put it over West epoxy resin. Nothing that a scraper, old towels and a bucket full of acetone couldn't fix. Used mask, gloves etc as it was very confined, awkward space.
Thanks for all the input and advice.
Lesson learnt!!

Polyester resin is a totally different animal. You mentioned epoxy in your first post and never said you switched materials between the first and second coat.

That totally changes the rules.

[UNCIVILIZED]

Originally Posted by valhalla360

Polyester resin is a totally different animal. You mentioned epoxy in your first post and never said you switched materials between the first and second coat.

That totally changes the rules.

Yep, EXACTLY! That's a big, big error in ettiqute. What were you thinking?

[amoret]

I had no idea you could get epoxy flocote and polyester flocote.

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[amoret]

Oh and very sorry for any confusion.

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[JOHNMARDALL]

Originally Posted by Cheechako

I have had problems with paint curing over epoxy before also. Not sure why. In some cases "epoxy paint "with "epoxy paint" overcoat over it. I don't think those paints are actual epoxy but not sure though.
I wonder if you wiped the surface with vinegar if the tacky would go away? Vinegar is used for clean up of epoxy right?

I doubt it- vinegar works as a clean up solvent for uncured epoxy, but if you're going to try it, experiment on a very small area, in case it goes badly. As the OP has indicated that the flow coat is catalysed with MEKP (methyl ethyl ketone peroxide) the flow coat is a polyester/ vinylester product
John Mardall
Vetus Maxwell Group

[JOHNMARDALL]

Originally Posted by Cheechako

I have had problems with paint curing over epoxy before also. Not sure why. In some cases "epoxy paint "with "epoxy paint" overcoat over it. I don't think those paints are actual epoxy but not sure though.
I wonder if you wiped the surface with vinegar if the tacky would go away? Vinegar is used for clean up of epoxy right?

I doubt it- vinegar works as a clean up solvent for uncured epoxy, but if you're going to try it, experiment on a very small area, in case it goes badly. As the OP has indicated that the flow coat is catalysed with MEKP (methyl ethyl ketone peroxide) the flow coat is a polyester/ vinylester product

[elbib]

Looking over the post I made, I mentioned that just coating your tacky polyester with epoxy is the way to cure the problem, I know because I've done it and know it works. If you're hesitant, just coat a small area and see the result after the epoxy kicks off. Clean up of the tacky resin is going to be a mess at best, and in a confined area, it may make you sick. Try it, you will thank me!

[UNCIVILIZED]

I'm unclear about the flow coating comment regarding the two resin types. But with epoxy, flow coating can be & is done with most different "types" of epoxies. It's more in the application technique than anything else. At least as I've done it.

As the term "flow coat" is one which basically describes the same thing which happens when using a quality paint that's been properly thinned. The paint (or resin) simply flows over the surface, & self levels to a smooth, even surface, prior too hardening. So that when things do harden/cure, you have a nice glossy, even finish on things.
They're all resins of one type or another. Just optimized for different properties is all.

[JOHNMARDALL]

Originally Posted by elbib

Your not the first person to have this problem, the cause is probably the use of polyester laminating resin over any substrate. That resin is designed to be used in a mold or any airtight system such as a vacuum cure.

The simple cure for your problem now is to coat with epoxy, sand if necessary, then you can finish with an epoxy primer and paint.

Laminating resin is designed that way so that it does not need sanding from one layer to the next. The last layer will have to be a finishing resin, finishing resin has a wax or something similar mixed into the resin that rises to the surface during the cure, therefore restricting the air.

Lew on S/V Allusion

As this flow-coat material is described as containing wax, it is not a laminating resin, but a top coat/gel coat product. The wax migrates to the surface and seals it, allowing a non-tacky cure. Laminating resin is air-inhibited and will stay tacky until it is sealed. Adding another coating over a cured waxed product usually requires removal of the wax, with solvent and sanding.

John Mardall
Vetus Maxwell Group

[Jim Cate]

FWIW: HEre in Oz, the term "Flowcoat" refers to a specific product, and it is a thin polyester based resin designed to be used as paint, usually over fiberglass structures also based on polyester chemistry.

So, ragging on the OP for being unclear is not justified IMO.

Jim