Hi again. I use GC50 gelcoat for all our products. We are new in using this product, I'm having hazy clear coats after a week or two of exposing it to sunlight. At brand new condition there are no problems. I sprayed the GC50 with gelcoat spraying gun. Single layer. I use vinyl ester resin for vacuum infusion. Any solutions?

Hi, I have only ever had this with GC50 when moisture from my compressor contaminated the GC50 during spraying. I had a water trap but it clearly wasn't up to the job. Replaced it with a better separator unit and have had no issues since.
Is there a separator on your compressor and is it humid in your workshop? It may be worth fitting a inline filter just before the gelcoat gun as well, condensation can form in the air line.

Warren

Carbon Copies Ltd

Hi wozza, I work my gel coat in an enclosed room. We actually have filters. 2 of them before the spray line. I have attached photos. Thank you

I would still check the airline for moisture. Try spraying onto some kitchen paper with a clean empty gun.

Warren

Carbon Copies Ltd

We actually occasionally check the line for moisture. We also use it for chroming, which cannot have moisture, car paints and clear coats.  Be assured that, that one is checked. Thank you

As far as I know the GC50 is not really compatible with Vinyl-ester resin?  So what you are seing may be delamination between the GC50 and the vinyl-ester below it ?

The EC staff should be able to clarify (no pun intended) this?

The product description clearly states that GC50 should not be used with polyester resins.

"Sapere Aude"... Dare to KNOW!

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103% of all people do not understand statistics...

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Dravis is correct. GC50 was formulated to make a bond with epoxy which means it doesnt bond well with polyester or vinylester due to the different chemistry involved. 

I suspect delamination is the issue or some other kind of chemical reaction due to incompatible materials - maybe even outgassing of the styrene.

Vinylester works like polyester in that it is loaded in styrene and that all has to evaporate somewhere.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

A simple solution to this problem may well be to use polyester Gelcoat, instead of GC50 ??..It's cheaper as well .. And highly UV resistant.

"Sapere Aude"... Dare to KNOW!

The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...

103% of all people do not understand statistics...

Do not adjust our mind, theres a fault in reality :-)

noted! Thank you.