Hello I am new to this forum and the Composites Industry. This was my second time making a Carbon Fiber panel, I will be trimming several RC car pieces out of this Panel.
The first time I did not use vacuum bagging materials and this is how it came out, rear glossy and stiff.
 

I use Partall wax #2 and PVA from Fibreglast as my mold release agents. I use a Sheet of home depot glass for my glossy side.

This second time I used the same glass surface and the same release agents. I tried experimenting with vacuum bagging materials and used a slower hardening Epoxy resin.

I used 4 layers of 3k 2x2 Twill carbon the size of this is around 12"x16".
I applied vacuum for around 20 minutes and noticed it had a significant leak in one of the corners where the tacky tape joined together.
I resolved the massive leak. left it over night in my shed with temp around 70 I assume(Didn't check)
checked it in the morning and it had no vacuum, probably another leak.
This is how it came out


I suspect that this distortion was caused by a leak in the system or wrongly mixed epoxy.
Any advice is helpful and wanted.
Thank you for your time.
-CarbonBro

Forget about vacuum bagging method, you will not receive good carbon fiber visual surface from this method.
Use resin infusion method instead.



Carbon fiber sheets and composites .
www.dexcraft.com

Is  it not possible to sand it flat, then add another layer of epoxy, sand that flat and finally polish to a mirror finish?

I have not tried this myself but have seen this on youtube and using intuition??

I am pretty sure you can get a good finish with vacuum, you just need less vacuum. I think there is an easy composites video tutorial on how to do it.

Or you could do the first layer wet laid and careful, then leave this for a few hours to gel and then add the rest of the laminate and vac bag with full vacuum using perforated release films etc.

Yes Fasta is right.  We tend to recommend around 20% vacuum as a starting point then vary up or down to get the desired cosmetic finish.  You can see our video on a simple vacuum bagged part here:  



Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant