Hi guys,

I'm hoping somebody can help me with this ......................  >>


I'm currently making 2 headlight covers tooling plugs using EC' Vac-Cast Epoxy Resin.  I followed the entire procedure as per the instructions,  my first cast turned out superb,  my second cast ( image above ) ended up with hundreds of tiny little white specks on the surface!  

The white specks are on top of my tooling plug,  no white specks on the sides or bottom of the plug.  As the cast was done upside-down,  the top of the tooling plug would of been the bottom of my silicone mould.  I used the aerosol MANN 200 silicone release on both plugs,  so if the release agent would be at fault,  both plugs would of ended up the same,  but they didn't ..............  just this one.

You can't feel the white specks when running your fingers lightly on the surface,  but I'm a little concerned that they're going to cause problems on the next stage as I need to vacuum form transparent PETG or Polycarbonate to vacuum form the headlight covers.

Would anybody have any idea what caused this please?


Many thanks for your time.



TURK
T4 Concepts

Very strange that it is on one not the other.  Anything that could have got into the resin during mixing? or something falling lightly into the mould?  Assuming both pours came from same resin batch and it was well mixed etc then I can't think of anything in the resin as a contaminant - seems too small/light to have sunk through the resin.

Does it come off with light sanding or a a quick polish? It almost looks like tiny air bubbles on the surface that have filled with polish or sanding dust or similar.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Hi Warren,  many thanks for the quick response mate.

Interesting that you should mention 'polish',  small bubbles being filled with polish!
Could well be mate.

I found it rather strange that during the entire process of making resin tooling plugs,  you must first make your positive plug ( PU foam and Pattern-Coat Primer ),  then buff to a very high polish,  glass like finish.  You then make your negative silicone mould,  then cast your Epoxy Tooling Resin into that silicone mould.

PU foam and Pattern-Coat Primer >>


Unfortunately EC's Ease Release isn't compatible with the CS25 Silicone,  so you have to use the MANN 200 release agent,  but as it's states on the aerosol can "Will give a satin finish",  and it does,  a nice matt finish that needs an awful lot of polishing!  In fact,  just polishing doesn't actually give you your high gloss finish back.  In my case I had to use Farecla cutting compound!

I begin with Farecla G10 and then move onto Farecla G3 which is much finer,  then I can move onto the polishing stage ................  works quite well actually 

I didn't degas the Vac-Cast Epoxy resin as it says it's not necessary,  now having seen the results I would say that it does need degassing!  Right from the get go I knew I was going to vacuum form transparent plastics like PETG and Polycarbonate ( automotive headlight covers ),  so I really should of degassed the resin.  I won't be making that mistake again!

It makes great sense in what you're saying about tiny bubbles being filled with polish ( or Farecla in my case ),  you certainly can't feel the tiny whites specks,  that's probably because they're filled with hardened rubbing compound!

What other methods do people use to 'polish' to a very high gloss resin tooling plugs?

Just to add to that .....................  I've just ordered from eBay ( ebay France ),  some 'Micro-Mesh' abrasive pads,  fine grits from 1500 to 12000 grit.
Anybody here used them before?




Thanks for your time guys 




TURK
T4 Concepts

The release agent doesn't help for sure.  You finding you are getting sticking on the CS25?

I think like most epoxies, Vac Cast is sensitive to  temperature this time of year - certainly the viscosity increases the cooler it is which may well have an effect on the small bubbles we think may be causing your problem.

The grit range on those pads sounds good and certainly goes plenty fine enough.  As long as they are good quality discs then you should not have any major issues.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

I warren,

Yeah,  it was a bit touch n go getting the temps in my workshop high enough,  but with both my oil heaters heating my workshop for a week I did manage to get a steady 23°C 

I didn't get any stickyness from the silicone moulds at all,  in fact, they turned out superb.  Notice the nice glossy finish of the Pattern-Coat Primer Resin plug,  that was well detailed into the CS25 silicone mould,  also nice and shiny!.  It's unfortunate that the result is a matt finish after having to use the MANN 200 release agent  >>



The 'Micro-Mesh' are actually soft sanding pads and not discs, they can be used either wet or dry .............  guitar makers and jewellers use them for high gloss finishes.  I'm thinking they might be the answer for polishing resins to a high gloss finish as opposed to using Farecla,  or any other polish.  I can only but try     Technologies are even making great advancements in the sanding world!  these haven't been on the market all that long,  they're like a very fine cloth abrasive.

D'you think I should finish off with  'Autoglym Super Resin Polish'   ?
Baring in mind that I will be using these resin tooling plugs for vacuum forming transparent headlight covers.


I'll let you know how I get on.  Who knows,  this little post may help other guys out when making resin tooling plugs,  and how to get that perfect finish    





TURK
T4 Concepts 

I'm surprised you need a release agent when casting epoxy into CS25. Epoxy doesn't generally stick to silicones.  Maybe ditch it and retain the gloss?

The pads sound ideal.

I wouldn't use Autoglym SRP on a car let alone anything composite. It's probably fine for those who use a scratchy sponge to wash their car or parts but if you want genuine gloss then avoid it.  This is because it is full of fillers.  Sure they fill in scratches and make it look shiny initially but it has a very low amount of abrasion so it doesn't remove many scratches.  The fillers wear off fairly quickly.

You are better off using a proper polish which  will remove the scratches rather than mask them.   That's generally the problem with a lot of "retail" automotive products - the people they are aimed at want quick and easy results rather than longevity. The detailing type brands and products tend to be better.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant