polyester flow coat

stu9000

stu9000

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Morning !

I have painted my rudder three times with poly flow coat gel paint but it still shows brush marks and I am disappointed with their finish. The catylist mix is right and I pre heat the shed so I think the temperature is ok.

I could sand down and wax or look up some kind of lacquer.

Any suggestions?

Thanks


S
 
I use a fair bit of this and have found that you must adjust the amount of catalyst to compensate for the solids in the resin.

Try a test bit with half the catalyst you have been using and check the results.

Good luck and fair winds.
 
stu9000 said:
Morning !

I have painted my rudder three times with poly flow coat gel paint but it still shows brush marks and I am disappointed with their finish. The catylist mix is right and I pre heat the shed so I think the temperature is ok.

I could sand down and wax or look up some kind of lacquer.

Any suggestions?

Thanks


S
Click to expand...
Would normally suggest exactly what Bobc has.

Unless I'm getting confused or there is a product called poly flow coat gel paint;

It won't self finish like a paint would, but a roller would have helped.

Have you removed the wax layer with each coat?
The flow coat is simply gel coat with wax added, but if you have coated over this, without removing the wax layer, it will be rejected by the next.

In short, the first two coats should have been without wax.

Has it all cured?

Tony
 
Marine Reflections said:
Would normally suggest exactly what Bobc has.

Unless I'm getting confused or there is a product called poly flow coat gel paint;

It won't self finish like a paint would, but a roller would have helped.

Have you removed the wax layer with each coat?
The flow coat is simply gel coat with wax added, but if you have coated over this, without removing the wax layer, it will be rejected by the next.

In short, the first two coats should have been without wax.

Has it all cured?

Tony
Click to expand...

It is called "polyester flow coat" and comes from a place in Wales. Got it off EBay. Fairly non branded I think and very little info on the label.
I sanded down between coats.
Yes it has cured.
I didn't use a roller.

I guess I need to decide whether to try another coat with less catylist or buy in some polish.

Thanks
S
 
I guess what you've use is Polyester flowcoat from Llewellyn Ryland.

Just sand out the brush marks and polish. It'll be fine.
 
Marine Reflections said:
Would normally suggest exactly what Bobc has.

Unless I'm getting confused or there is a product called poly flow coat gel paint;

It won't self finish like a paint would, but a roller would have helped.

Have you removed the wax layer with each coat?
The flow coat is simply gel coat with wax added, but if you have coated over this, without removing the wax layer, it will be rejected by the next.

In short, the first two coats should have been without wax.

Has it all cured?

Tony
Click to expand...

Hi,
I am very new to gelcoats. can someone clarify the difference between gelcoats and flowcoats. also my understanding was flowcoat needed wax added to set, is this the case. any guidance much appreciated.

Steveeasy
 
steveeasy said:
Hi,
I am very new to gelcoats. can someone clarify the difference between gelcoats and flowcoats. also my understanding was flowcoat needed wax added to set, is this the case. any guidance much appreciated.

Steveeasy
Click to expand...

G'day Steve,
Flow coat is Gelcoat with wax added, it's that simple. Gel coat needs to covered (usually a plastic like cling wrap) to exclude the air or it will not go off.

Best applied with an 80mm roller, that's the bog standard pink roller you see in the hardware shops.
Buy the standard pink roller but the long one so you can cut into 3 x 80 mm lengths.

I stand the mix in a container with some warm water before I start and make sure the surface I'm coating has a bit of sun on it first. Put you hand on your skin and the job and they should be about the same, same for the flow coat mix.

Mix a batch using about half the catalyst you would for that volume of resin because most of the product is solids that need no catalyst. adding less catalyst prevents it going off before it self levels.

There is another technique that uses lots of very thin coats rather one single heavy self levelling one.

Simply roll (not too thin) and lay flat if possible. throw the roller away when finished. Job done.

Good luck and fair winds. :)
 
Last edited:
oldsaltoz

When laying the initial coats of gelcoat (no wax) at what point does it need to be covered? Presumably after it has self levelled and at least got to a jelly like state?
I've been thinking of renovating the cockpit so I would need to coat areas of the cockpit seat, the seat edges and the vertical surfaces to the cockpit floor. Is this a candidate for flowcoat. What sort of surface area is 'doable' at one time?
 
I only use flow coat, gelcoat it just too much fiddling around for large areas in my opinion.

As for what size area in one go, I have coated an entire swimming pool in day. It would have been less but I had to wait for the sun to around and warm the other side.

Best applied with a roller and always maintain a wet edge, or be prepared to do some extra sanding.

A cockpit would first have to be prepared, filling and sanding any damaged areas and sanding the rest to ensure a good bond, then a wipe with Acetone just prior to coating.

You should buy a small quantity and have a practice, perhaps the underside of the cockpit seats first then move onto the tops. they can be removed and done at home.

Try both methods of application to see what works best for you.
Method one, apply several ( 5 or 6 ) thin coats, no chance or getting ridges but time consuming.
Method 2, roll onto the surface with enough material for single coat and maintain a wet edge.

Good luck and fair winds.
 
Yes i am using the welsh stuff.
Someone asked earlier if it had set. There was one small patch that had not. I put it down to poor mixing but it has done it again in the same place. This spot is a repair I did with epoxy resin . I will have to clean the gunk off with acetate and will try priming it with a can of car spray primer. Will flow coat not set over epoxy? Weird.
 
stu9000 said:
Yes i am using the welsh stuff.
Someone asked earlier if it had set. There was one small patch that had not. I put it down to poor mixing but it has done it again in the same place. This spot is a repair I did with epoxy resin . I will have to clean the gunk off with acetate and will try priming it with a can of car spray primer. Will flow coat not set over epoxy? Weird.
Click to expand...

Polyester doesn't like epoxy.
 
oldsaltoz said:
I only use flow coat, gelcoat it just too much fiddling around for large areas in my opinion.
Click to expand...

Howzat work, then? Surely if you're laying up in a mould, the wax will rise to the inside surface and stop the first layer of resin adhering properly?

I go the other way round, and only buy gelcoat. If I need it to go off in air for a particular job then I add the wax.

Pete
 
Just to say , using a roller and less cataylist has helped. Not perfect but ok for now. Thanks for the tips.
There is still the section on top where I did an epoxy repair to the gell coat. I sprayed with a can of car primer but was quite surprised to see the flowcoat still would not set. The rest of the batch set fine. Seems weird to me. I dont get it.
 
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