Hi folks,

I've been using the above on my current project (model aircraft) and have been impressed with it's hardness when cured. But I find it's quite thick to brush on and doesn't flow very well, leaving quite an irregular surface .  Is it possible to thin it slightly so that it flattens out better?




Many thanks, Marty

I wouldn't recomend it.  Can I ask why you need to use epoxy tooling gel?  I currently use polyester tooling gel and I find that cures to a nice, hard, polishable surface. This stuff.  I use it for all laminates without problems.

what epoxy tooling gel coat are you using?

Hi folks, 

Apologies for the late reply - been away.

I've been advised not to use polyester for the moulds as the plug is made from foam and may suffer if it gets too hot and I'm building the finished model using epoxy, GF and carbon.  The tooling gel coat is Easy Composites  https://www.easycomposites.co.uk/epoxy-tooling-gel-coat

Maybe a synthetic brush might put it on smoother?

Thanks for your input guys, Marty

The issue with foam and polyester is down to the styrene melting the foam if its the wrong type.  You can seal the foam with a coat of epoxy or use the right foam.  For example I have recently made some wing mirrors.  I used a non-stable foam and coated it with epoxy.  I took moulds from this in polyester gelcoat.  I then made mouldings in carbon / epoxy from the polyester mould.  I see no reason for concern.    However, if you really want to use epoxy then try putting it on thick and you should be fine as its the surface next to the plug that matters.  Alternatively you can wait for it to start to thicken and then smooth it out as it gels.  Out of interest whats your model?  I'm currently building a gas turbine.

ETA:  Been away anywhere nice?

Hi FLD,

Yeah, the plug is glassed and epoxied (see attached) but another reason for using epoxy is that my workshop is attached to the house and polyester is just so smelly! 

The model is a 1/8th scale of a Westland Wessex Mk1 - 6ft from nose to tail. going for electric on this one but may go turbine on the Mk5 version.

Cheers, Marty

Wow!  That is some plug, I'll bet there's a few hours work in that.  I completely agree with your choice of epoxy if you're near your house.  Polyester does smell rather.  I always try to be outside when I use it.

why put it on smoother ? dont see that its going to make a difference ?  what you can try is to warm it up a little and mix smaller quantities at a time
 

also , try running a blow torch over the first layer of toolcoat to pop any bubbles

A flame produces lots of carbon dioxide and water vapour. Not good with amines. I'd rather use a hairdryer or heat gun.

I'm guessing you're using it to coat something and desire it to lay flat to give a regular surface, say plug production or surfacing a tool. And not using it to capture the surface of a plug, as the surface detail would be replicated and thus the regularity in the surface not an issue.  Try using a less thixotropic resin or adding in a wetting agent to decrease the surface tension. I've tried a number of wetting agents and a very smooth flat surface can be achieved on the surface of a plug simply by brushing on a regular epoxy treated with a dry wax teflon out of a spray can at 1-2%.