New Member
Hi, i have question about resins. What kind of resin should i use to cast bio? What is the diffrence between epoxy resin and polyurethane resin? And does polyurethane resin mean fiberglass?
Becose some time ago i did my first cast of bio. I used a polyurethane resin with the fibre and it was not that bad, but when i compare it with the material that my new mysteria P2 is made of, then its realy bad :p . Its much more stronger, massive and seems realy solid. Could i use epoxy resin for a bio?

Thanks Joseph


Well-Known Member
polyurethane resin is NOT fiberglass. pu resin is alot lighter. and stronger when it comes to durability. i have never used epoxy resin so i can not comment on that one.

Cavaler Urban

New Member
I know pu resin is use with fiberglass armature ,epoxy resin is use when you work with carbon fiber! pu resin it's more easyer to work with!


Sr Member
For Bio Helmet alone

1:1 Ratio PU Resin plus fiberglass chopped mat is the material I use. The Glass Fibers absorb the mixed liquid resin and gets hard after few minutes. All my Bio's are made this way and it can build-up layer and becomes very strong and light. Epoxy resin is the dark grey and black kind, some people use it and I have some Bio's like Biohunter76's Wolf is made with that stuff but no fiberglass. Its lightweight and strong as well. I also got a Ruffkintoy's Celtic bio made with Bondo the first layer then resin backed fiberglass. All together very heavy and strong. My P2 BIo made by Hez is a resin only Bio and its also very light weight and thin. So you have many materials to work with and they are all dangerous chemicals and require Gloves and Respirator. So read all instructions/ warnings and work in a well ventilated space. Good Luck!


New Member
Thank you for the info guys. Btw i messed up two types of resin, i used polyester, not polyurethan, but when you Uratz wrote the mixing ratio 1:1 i realized that. This resin i used is like 100 : 4 ratio, so thanks again :p
Now am going to order some polyurethane resin and see what thats like.



Sr Member
Correction Mike, I don't use Epoxy resins in my bios. The black color comes from pigment added to polyurethane resin. :lol:

Doh :p I noticed that you used the gooey kind where I can see finger marks pushing the resin around in the WOLF bio so I thought it was the Epoxy type.
My PU resin is pretty liquidy and gels when it start to harden and gets hot!


New Member
You can use epoxy resin with fiberglass, although I never have. Some people swear by it because it is stronger than polyester resin, and also it does not give off the harmful fumes that polyester does. As you noted, polyester and polyurethane are NOT the same thing.

One thing to remember when fiberglassing is that too much resin is not good. You need to use as little as possible, just enough to wet the mat, not completely soak it. Plain polyurethane resin is much more user friendly, and easier to produce a quality item with.
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