The Zetec 'Ropacane

[gideon]

Epoxy resins shrink less than polyester in general and are more stable after initial cure.  Polyester resin loses styrene as it cures and so it loses volume.  It also continues to cure, and shrink, over a relatively long period of time (but how long - weeks, months, years?).  There are different figures quoted, but polyester resin shrinkage may be between 5% and 7% by volume, as compared to 2% or less for epoxy resins.

Some opinions here

https://www.researchgate.net/post/Epoxy_vs_Polyester_resin_against_volumetric_shrinkage_during_curing_process

[TurboFource]

Chuck,
Maybe just paint the rear of it so you can't really tell from behind until you walk up to it....
shame to hide all that hard work! Looking great

[Chuck Nukem]

Just an idle thought but I wonder if the carbon weave would eventually 'print through' the final paint like fibreglass woven cloth does.

This might be more a feature of Polyester resin. Does epoxy resin shrink to it's final form in a shortish time?
I really have no idea.

I'm not sure. I honestly wouldn't mind a bit of weave print through as it would look like an old F40... They say that you can tell if one of those has been wrecked because you wont see the weave after primer is sprayed on it during a fix.

Thanks for the kind words guys! The nice thing about having the mold is that I can make another to leave clear I already have ideas on how to improve the bond between the two sides. I bought several different types of carbon to experiment with and some might come out darker than others. Also I haven't seen it in the sun yet and that will really make the final decision.

[GavinT]

Epoxy resins shrink less than polyester in general and are more stable after initial cure.  Polyester resin loses styrene as it cures and so it loses volume.  It also continues to cure, and shrink, over a relatively long period of time (but how long - weeks, months, years?).  There are different figures quoted, but polyester resin shrinkage may be between 5% and 7% by volume, as compared to 2% or less for epoxy resins.

Some opinions here

https://www.researchgate.net/post/Epoxy_vs_Polyester_resin_against_volumetric_shrinkage_during_curing_process

Interesting answers on that link, Gideon.

But can they be right?
I could believe small percentage shrinkage for either resin, but 5% or 7% sounds implausible. At those rates, parts would literally fall out of a mould and a Europa body would end up roughly 6 inches shorter than the mould!

There's one guy who sounds like he might be closer to my (imaginary) understanding:

Are we talking here about epoxy and polyester without additives like fillers etc.?
If that's the case then there isn't such a big difference between them. Polyester shrinks a bit more (1%) compared to epoxy (up to 0,9%).
Shrinkage also depends on the process (injection, transfer molding ...).

[gideon]

The shrinkage figures are for volume - 5% shrinkage by volume is about 1.6% linearly, or 2.5 inches over the length of a Europa.  But that figure applies to just resin by itself. Where the resin is supported by fibers it won't be able to shrink so much - except maybe in thickness.  Coming back to Chuck's engine cover, there should be less print through than if it were made with polyester, but either way the fiber to resin ratio will have an influence on how much print through there is in the end.

[Chuck Nukem]

I thought I would be done with this by now... I stopped measuring time in hours and began using Rossini's "William Tell" to keep time.

[BDA]

Looking good Chuck! “William Tell” is a long opera. Hopefully things will go faster soon so you can pick shorter operas… maybe “Tommy”? 

[Chuck Nukem]

The way things are going it will be Wagner's ring cycle 

[Chuck Nukem]

Gold leaf is down! It looks amazing in person. Clear tomorrow!!

[BDA]

She’s looking good, Chuck! Can’t wait to see her after the clear coat!

[SilverBeast]

  Looking pretty awesome in the photos too!

[TurboFource]

Nice!

[S2Zetec54]

Terrific…love the way the gold line tapers so nicely

[Chuck Nukem]

One last peek before clear

[Chuck Nukem]

Here she is!