Good morning, this may prove a tricky question to answer but who doesn't love a challenge!


First a little background information. As a University we have been making moulds and parts from polyester resin for almost 20 years but now want to try and reduce our carbon footprint, as well as giving our students a safer working environment by switching to a bio based epoxy resin system. We have chosen Super Sap from Entropy. Obviously there is a significant cost increase associated with the epoxy over the polyester but due to many benifits of the Super Sap we are willing to invest heavily in this.

There is however one main issue. The lack of an epoxy gelcoat that is compatible with this system. The only way we can justify switching fully to epoxy is if the process that we currently employ with polyester remains the same.

So my question is has anyone found, and is using, a decent epoxy based gelcoat for hand lay-up? Obviously I'm aware of the many 'Epoxy Compatible Polyester Gelcoat' options but the big selling point of using Super Sap is the very low VOC's meaning no repiratory equipment is needed, so would be a step backwards if we had to use Polyester alongside this.

Having spoken to Entropy, they do not currently make a gelcoat so I've taken it upon myself to research into this and hopefully others will find it useful. Ultimately what we need is a clear epoxy gelcoat that can be pigmented much the same as a polyester can, is polishable and hard waring. Not too much to ask for!

There may well be a good reason why an epoxy gelcoat doesn't seem to exist when there are countless polyester options, but as I'm not a chemist I cannot see why one wouldn't work.

Any help / advice / criticism is greatly recieved.

https://aub.ac.uk/

I Suspect the lack of commercial demand in significant quantity is why you can't get hold of anything. Clear epoxy gelcoats do exist but for many processes using parts made of epoxy, a gelcoat isn't strictly necessary.

I am not aware of any environmentally friendly epoxy gels on the market at present.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Thanks for the quick response Warren. Are you able to send me a link to any available clear epoxy gelcoat options? All I'm coming up with are the Epoxy Compatible Polyester ones.

I wonder whether we are being foolish trying to switch to epoxy for mould making? Do people actually make moulds soley from epoxy rather than polyester or am I barking up the wrong tree?

Thanks, Ben

https://aub.ac.uk/

We don't actually have any clear epoxy gelcoats at present.

A lot of customers use vinylester based tooling gel coats on their moulds as the vinylester can be used with a variety of resin systems including epoxy.  Take a look at our Uni-Mould Complete Mould Making Kit which is commonly being used with epoxy for resin infusion and out of autoclave pre-preg.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Epoxy moulds are big in the aerospace industry. I've used the Airtech Infusioncoat, which is excellent. However it is bloody expensive stuff at around AUS$8500 for the 25kg kit. 

I have done a number of small moulds and parts just making my own epoxy gelcoat from the base resin with some thixotropic powder (cabosil) and also a little pigment just to get some colour.