resin casting into wood

[Zsolt Paul]

Hey all! I have a lot of experience working with epoxy resins, but not so much with making and casting into silicone or rubber molds. We don't ever duplicate existing "positives". I would like to create a 3D negative and cast (and remove) the positive directly into it. I would like to bypass the mold making step if possible. My questions are:

1: Is it possible to cast epoxy resin directly into wood and then remove it with the right kind of release agent? We had tried, and had good success with paste wax, but would rather avoid using wax, as it can contaminate adhering/coating afterwards).

2: Alternatively, is there a rigid material that I could carve/laser into to use as mold, then cast resin that would easily release from it (without the use of wax)?


As you can see, I'd like to bypass the additional step of making a silicone or rubber mold, since we have the capability to carve the negative. We don't ever take existing "positives" that we need to copy via traditional mold making/duplicating.

Thanks much!

[Rodne Gold]

You *can* do it , you can use any manner of materials as a mould so long as you seal any porosity and have a mould release agent that works ..HOWEVER if you bypass the silicon mould process and use a rigid mould , you CANNOT remove stuff with slight undercuts and even some stuff without undercuts could present major removal difficulties. You will also have difficulties with lasering or CnC engraving/routing smooth and flat surfaces directly into the moiuld material. Large area hogging has a bad surface finish with a laser , especially in wood where material density and resin content varies big time.
Worse than that , you have VERY little control of exact depths of engraving with a laser..

It's generally easier to make the master with your laser/CnC engravers/routers and then hand finish them to a high standard and make a mould. You then have a master for reference and can create as many flexible moulds as you want and do some severe undercut work as well.

[Zsolt Paul]

Thanks Rodney. Your points are valid indeed. However, the reason why those negatives (no pun intended) are of less importance to me at this particular phase, is b/c I do not need more than one of any particular pattern. We are making samples. I agree, for multiple duplication, having a master will be the way to go. Assuming wood will be the master, which release agent would you recommend to release epoxy from wood? We will not have any undercuts by design. So far, using paste wax, the epoxy came out very well, all details showing perfectly, I just don't like using wax, that's all.

Any suggestions RE #2? Is there such a material that would not adhere to epoxy and release it without any wax or release agent?

Thanks!

[Mel Fulks]

I'm sure you will get some good answers here, but one of the best places to buy those from is a pattern makers supply.Modern pattern makers use a lot of products that require release agents and they have different types and will make suggestions based on the material.