Talk Composites - The Forum for Advanced Composites

Breaking in mould. Does anyone do it? My moulds stuck!

http://www.talkcomposites.com/Topic40197.aspx

By carbon man - 6/16/2021 8:46:22 PM

So Iv had 3 moulds stick on me now. I'm using tr108 wax as it's advertised to reduce fish eye when gel coat goes into the mould.

I have tried exact instructions on tin 8 coats and then leave over night before another coat.

Also tried 5 chem release followed by 2 tr108 wax.

I brush in polyester gel coat let dry. Lay up and  infuse with epoxy In2 resin and cure in mould at 60deg straight away for about 8 hours so it gels fast in the event of a leak.

The shiney parts of the mould released just about but everywhere else stuck like s***!

But should I be laying in a layer of fibreglass and pulling that out once cured to break in mould first?

Any help appreciated.
By carbon man - 6/29/2021 8:23:11 PM

Hanaldo - 6/29/2021 5:01:33 PM
carbon man - 6/28/2021 3:46:44 PM
Hanaldo - 6/23/2021 9:04:29 AM
carbon man - 6/22/2021 5:20:16 AM
Hanaldo - 6/22/2021 12:05:16 AM
carbon man - 6/19/2021 8:11:50 PM
Hanaldo - 6/19/2021 3:07:21 PM
Ah, that's different then - Crystic Glosscoat isn't a gelcoat, it does cure solid and epoxy can bond to it.

Breaking in moulds is definitely a thing. Though if you can get a semi-permanent tool sealer, then this will treat the chemical and physical bonding sites of a new mould in the same way that breaking them in does. So I never break in any of my new moulds, because they always get treated with a sealer first.

Awsome glad to hear that because I love the gloss coat it dries smooth with no brush marks.

Have you had much experience with gloss coat? I guess it's a ok product to use as a clear coat. It seems to dry and polish up great

I have tried Tr102 wax took a bit of brushing with the gloss coat to remove fish eye but all looking good so far.

I think the problem is tr108 wax. It just doesn't leave my moulds smooth, almost a matt Finnish then they stick.



Yes I've used Glosscoat a lot, probably gone through a good 250kg in the last couple of years. It's OK, there are better products out there - I dont like how red it is, and it does change the colour of your finished part. Not the most noticeable thing, but it is noticeable.

Definitely sounds like there is an issue between your gelcoat and the TR108, I also use TR108 a lot and it certainly never leaves any sort of matte finish, so that's a bit strange.

You say better products out there? Which do you recommend that can be brushed in mould and dry smooth with no brush marks? 

As per my comment in your other thread, you're just asking a lot here. All of these products are made for spraying, brushing is a compromised technique and as such you will have compromises in the result. 

Brushing without fisheyes requires a very thixotropic material. The less thixotropic a material is, the easier it will fisheye and sag. Thixotropic means resistance to movement without shear stress (brushing), so the more thixotropic a material is the less it will self level and the worse your brush marks will be. Thixotropic additives also tend to effect clarity, so clear gelcoats are generally not as thixotropic as opaque coats.

You say you have a lot of experience with gloss coat. As I'm using it as a final clear and looks and polishes up great! Do you know if there is any UV stability to it. I'm using easy composites in2 epoxy resin with it. 

If not. How long could I expect until the carbon started to fade. 

Thanks




No, there's definitely no UV protection. How long it will last is a tough one, it depends how much UV it's exposed to. Here in the Australian summer, it doesn't last 2 months outside. Loses all gloss and turns a chalky sort of white. Horrendous. Perth summer is about as bad as it gets though, so elsewhere in the world I would expect it to last a bit longer. But I would be surprised if it still looked good after 2 or 3 years. At the end of the day Glosscoat is formulated and intended for pattern coating, not as a finishing coat.

If you want it to last, use a top quality polyurethane. House of Kolor Show Klear is the best I have found. Have had a test piece sitting outside my workshop in full sun every day for the last two years, occasionally I think about it and go dust it down - still looks as good as the day I sprayed it.

Thanks for that. So I need to find something uv protected I can use in mould. Even if it means spaying it in I don't mind.

What I'm trying to avoid as Iv come from prepeg is trying to avoid spraying the part after with 2k clear. It takes up so much time for me as its not my full time job I struggle.

The gc50 easy composites sell doesn't dry smooth even when sprayed it's rough texture which leaves the finished part looking bad.

What If i sprayed 2k clear coat in mould would it release from mould and also would the epoxy stick to it? I believe duratec sunshield is best for the process I'm trying to achieve but it's not available in the UK.

Thanks Again