Talk Composites - The Forum for Advanced Composites

De-moulding issue with GC50 Gelcoat

http://www.talkcomposites.com/Topic10009.aspx

By wpackham - 3/3/2014 9:52:46 PM

Hi Guys,

I have just completed a resin infusion using your infusion epoxy resin. My mould is a gloss finish polycarbonate sheet. I applied several coats of easylease (per instructions) to the mould, followed by a brush applied coat of your GC50 Epoxy compatible gelcoat, followed 3 hours later by resin infused carbon reinforcement.

Unfortunately, 24 hours later, the part was stuck fast to the mould. When I removed it (with much force!) the carbon laminate came away from the gelcoat while leaving the gelcoat stuck to the mould surface.

I am trying to establish why this happened. I did use a standard MEKP catalyst with the GC50, not your catalyst product as shipping restrictions would allow me to purchase it with the gelcoat (I'm in Ireland). Is it possible that the MEKP I used was incompatible or past it's shelf life? Or could it have been a reaction of the easylease with the polycarbonate.

Your advise would be appreciated.

Wesley
By wpackham - 3/9/2014 6:25:10 PM

Having done multiple samples on both Acrylic and polycarbonate mould surfaces, I have still am not getting any satisfactory results with the GC50 polyester gelcoat.

I tried 8 samples in total, 4 on acrylic and 4 on polycarbonate. On the acrylic I tried 2 epoxy  carbon laminates with the GC50, one using easylease and one using No.8 mold release wax. The other two were epoxy only (no gelcoat). The 4 samples on polycarbonate followed the same format.

The results were as follows: The GC50 appeared to react with the polycarbonate mould surface (on both easylease and No.8 wax).The epoxy only laminates released nicely from both release agents on the polycarbonate.

On the Acrylic samples, the GC50 did not release well from the mould surface and it also did not appear clear or glossy as expected. The epoxy only samples released very nicely from both release agents.

I purchased a new bottle of MEKP from my local supplier, so I am pretty sure I can rule it out. To conclude, I have abandoned the GC50 in favour of using an epoxy only laminate as I am getting excellent surface finish on the Acrylic.

I would appreciate some input from the Easycomposites team as I have lost faith in the GC50 product.. I hope I have explained myself properly.