Experimenting with Plaster
Plaster is manufactured as a dry powder and is mixed with water to form a paste when used. The reaction with water liberates heat through crystallization and the hydrated plaster then hardens.
A photo of myself tidying up the plaster mould with my sculpting tools. Removing all alginate and unnecessary plaster blobs that may cause any abnormalities to the skin surface of the mould.
Plaster has been used in various situations throughout my projects as the cheap alternative to using any other mould, such as fibreglass. The advantage of using plaster is once you have finished using the mold, you can chuck it out and make another one. The use of using a much more expensive material which is not needed again seems a waste of product. Plaster was used to experiment with within my alginate mould.
A plaster mould of a hand was a cheap alternative for myself, knowing that the mould wouldn't be used again, and it may be the only option to completing a decent outcome that can work well within the given timeframe.
What have you used plaster for?
Here is the model hand that is placed within the curing alginate mixture. I had to combine two mixing cups together to form a barrier/ mould so the alginate didn't fall anywhere, an incision was made to the bottom of one cup. This also allowed the mould of the hand to have a thick mixture of alginate all around the mould to stop it from collapsing or tearing when the plaster is being poured into it.
A more clear view of the alginate inside of the mechanism I made to hold the alginate in. This was an easy option to do as the alginate would just slip out of the measuring cups and could be re-used for something else. The measuring cups acted as a good mould, and worked well whilst the model had her hand placed in the mixture. Once cured, it took a good 5 mins or more to release her hand from the mould as she found it a stuggle to free her wrist. Will some forceful tugs and pulls, her hand finally released and we had a great mould to work from.
Once the mould of the models arm was formed, you were able to clearly see the formed mould of the models hand at the bottom of the alginate cast. The picture without the flash didn't do it much justice, which pretty much showed how much depth was involved. With the flash on, you could clearly indicate where the fingers were, and the shape and textures of the models skin. It turned out really well considering it was my first attempt at alginating a different part of the body other than the face ( which I have performed many of times) .
Plaster of Paris was then mixed with water, and mixed well until lumps were no longer visible. A pancake mix consistency was then poured into the alginate mould until filled to the top of the measuring cup. I deliberately left a space between the alginate and the top of the cup so that the plaster was able to overflow, and create a small surface area around the plaster arm/hand, almost like it has it's own stand.
It took quite a few hours for the plaster to fully harden, at this stage the plaster was still slightly fragile and was still curing.
The bottom measuring cup was carefully pulled off of the alginate, this was surprisingly easy as the alginate was wet. The alginate is fully cured, and has formed perfect around the shape of the cup. I carefully made a small incision over the alginate, so I could start pulling away at the mould to reveal the plaster mould.
Here is the first process of peeling away the alginate from the plaster mould, I found this very time consuming and a lot of effort. The amount of alginate that was wasted was endless. 10 minutes later.....
....Eventually the plaster mould started to make an eppearance out of the alginate, which was more of a relief on my part as I was expecting it to not of formed correctly. I was slightly disappointed because as I was tearing away at the alginate, I can hear slight cracking noises comingf from within the mould, as if the plaste rwas so fragile that it was snapping. Most places around the fingers hadn't formed properly, and plaster seemed to of not reached places it should of, which was slightly disappointing. At this stage, I had to be extremely careful around the fingers when peeling away at the alginate.
Once the majority of the fingers had been explosed, the two fingers to right had not formed properly and snapped off, however the fingers that were mostly formed were the index finger, middle and thumb, which was basically all I needed to mould my sculpt onto. Again, the mould could of turned out a lot better than this if I had used a better moulding material. Overall, it was a decent mould to use to start experimenting with.
Unfortunately, the remaining fingers were so fragile that they split in parts, which resulted in me having to stick them together with glue. My model was unavaible for rescheduling the casting for the third time, so I had to make do with the cast I had already, and to be fair, considering it would be a one cast mould, which would then be thrown out, I didn't really see much point in wasting more expensive material. I did however clean the plaster mould up of any spare alginate remaining on the mould, and removed any blobs of plaster that were left on the mould using sculpting tools.
What did you like or dislike?
I always love working with plaster, alginate...not so much. Plaster is a great material to work with, although it is messy, so maybe not wear your best clothes when using it. A mixture of plaster has a great texture to it once thickened, and the simple method of just pouring it into the mould is a messy but fun process. The worst part of getting plaster on your hands, is that it dries them out, in my case, I always have to have hand cream about when I am using it, or a pair of gloves. The other dislike about using plaster is, you never know what to expect from a mould, whether it would break or turn out the way you want it to. Expect the unexpected...
How would you improve?
Perhaps using a different material to cast the hand would be considered next time. Material like life form or life casting silicone, where the mould captivates all the fine detail, and despite one mould going wrong, the use of silicone makes it re-usable. Again, silicone is expensive, and for not using this mould again, it would seem a waste of money if it was just going to be disposed of in the end.