by blacksmithn » Mon Jul 27, 2015 9:49 pm
My first attempt at resin casting was unsuccessful, in the sense that I didn't get anything usable as an end product. On the other hand, what I did get were a number of valuable lessons. I pass them on in the hope that others may find them useful:
1) Start with a flawless mold. Or, at least, as flawless as possible. In my initial attempt at a 2 part mold, I wasn't careful about laying down a smooth clay surface. I just pressed the clay out with my hands, making for a very uneven bed for the master to rest in. This caused problems later, as the clay pressed up against the sides of the master at different heights in different places.
2) Secure your mold halves with the proper amount of banding. I sandwiched my mold between two pieces of foam board and on my first try used four evenly spaced rubber bands to secure them. When the first try was not successful, for reasons I'll go into later, I retried, using only three bands applied haphazardly. This resulted in leakage from the bottom of the mold.
3) Speed is not your friend. When you hurry, you make mistakes. So, for me, I need to look for resin with the longest possible working time. In my case, what I had purchased has a 2 minute working time. On my first attempt, the resin actually cured before I could empty half of it into the mold. On my second attempt, I got about 2/3 of the resin into the mold before it cured, but about half of that flowed out the bottom of the mold, per item 2.
What I ended up with for my efforts was half a railroad flat car, from the top of the mold (since the bottom half ran out the end). It's quite a nice half, with cast in detail on the deck and underside that is really amazing to see. There's quite a bit of flash, some of which is easily removable and some which will require a lot of carving-- attributable to my error in item 1. But the possibilities that are demonstrated are remarkable. Important experience gained, I'm looking forward to retrying the whole process, starting with a fresh, much cleaner mold.