Hi,
Whenever I try to make a carbon part, the gum tape always sticks to the mold and it takes a long time to remove, but in videos online I see them taking off the gum tape effortlessly. I have used mold release wax specifically designed for carbon fiber.
What kind of plastic are the molds made of?
That depends more on which release agent you use.
its actually better that your sealant tape is sticking so well, but if it really bothers you and you would like to remove it with less effort you can put a layer or two of semi permanent release agent down. But I would recommend not.
If you don’t want to put a release agent down (I do), you can also consider just polishing the bonding line to a high(er) gloss. That’ll help with release while also insuring good adhesion.
What if the mold is already at a mirror finish? I’m not sure if I can get anything better than that unless there are a lot of nanometer sized scratches smaller than 405nm
It is a mixture of mold release, mold surface and the type of tape used. Some tapes clean up better than others.
As you are in a hotter part of the world, other tapes are used than in colder areas. What tape are you using?
I’m using the yellow tape from sollercomposites.com and I’m also using a tub of their mold release wax
I think the more important question is why can’t I get a mirror finish? There are almost always a tiny amount of dry spots where the carbon fiber was pressed directly against the mold itself and correct me if I’m wrong but I see people on Youtube making parts with a perfect mirror finish straight from the mold
The temperature is controlled to 68-73F
Genieiusxie…… your surface imprinting may be from the mold being green/new and curing additionally from the heat created from the process. It is not entirely uncommon to have to re-sand,re-polish a mold once its fully cured for production. Then, re-sealing and applying mold release. When you can….move up to chemical semi-perm release agents. Toss the wax to a buddy……preferably one you’d like to frustrate. 
Btw, do I need to use mold release for acrylic molds?
I have heard that you don’t need release agent for polypropylene because it doesn’t stick to epoxy. I would assume that it would be the same for acrylic because it doesn’t share any of the ingredients in epoxy.
Polyester, wood, concrete, etc all do not share chemicals with epoxy, but boy-o-boy, it does like to stick to them.
Basicly the only materials you cannot bond are:
Polyethylene
Polypropylene
Teflon
Delrin
All the rest: use a release.
What about natural rubber latex? I haven’t been able to get epoxy stick to that at all - like polyethylene bagging film. Not that I’m going to use a latex mold - this is for something else.
same for silicone. Works for a while, and suddenly it is stuck all over.
From what I have read within the last few days on new mold it needs at least 5 layers of wax and a good idea to use a pva over the wax but you would be better using semi permanent formulation for release where a sealer and release is used to give best results on a new mold. I gather this info from from a pdf put out by west system on vacuum bagging. Are you using a gelcoat?
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If you mean a coating of epoxy resin, then no, I’m not using a gelcoat
Btw, what is pva?
PVA is polyvinyl alcohol
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A release agent wich after applied forms a layer of plastic wich is dissolvable with water. Quite foolproof and if applied thick enough , will act as a chemical barrier. Hard to get a surface finish like wax will, but doesn’t need a polished surface. Sometimes applied with a base-wax, PVA alone can be quite sticky.
You can try using flashbreaker along the tape edge. Might change the surface enough. OR change tacky tapes. if one is sticking too much, another might be better. But yeah, if you dont have a seal, then it’s always bad if there is a leak!!!
Try using flash tape on then surface of your mold then place your gum tape down.
Try flash tape on mold surface, then apply gum tape over that should seal your bag and easier to remove when done.
Try pink tacky tape. It’s less sticky than the yellow stuff. I don’t know the brand but I have a bunch of pink that I stay away from if I can.