My goal is not to forge a Bocarina™, and certainly not to make a market with that (anyway, moulding and casting is much more expensive that buying the original nose flute!). Chris Schuermans had authorized me to experiment with a mould. Indeed, my goal is purely recreational.
[Sequel of the posts Part 1: Hard silicone, Part2: Casting urethane, Part 3: Low temp alloys and Part 4: Soft silicone]
Moulding and Casting - Part 5: Casting acrylic
I wanted to cast also acrylic resin, in order to (try to) get a translucent Bocarina™, because polyurethane is opaque. My hard silicone mould was beginning to be a bit worn, and I used my new soft mould.
The problem with such resin is that, contrarywise to the polyurethane which hardens in minutes, acrylic takes at least 24 hours to harden. In consequence, the smallest leak in the junction of the mould leads to a disaster: in 24 hours, all the content is able to flow out.
I was finally able to seal my mould with tape, and had only one refill to do after 12 hours. It took me 7 castings (one week:) to get one proper flute:
The other problem (that I have not totally been able to get rid of) is the formation of bubbles. When you cast the resin, you can lean the mould to avoid bubbles in some angles. But the acrylic resin produces bubbles during its hardening process. Micro-bubbles, but during the 24 hours, they have the time to gather in bigger ones.
For those, I had to make "patches" afterwards, that is, to re-cast resin in the little holes.
I also tried with a stock colored acrylic resin, and one in which I mixed a drop of red colorant (dedicated to polyurethane)
The results are funny, but not impressive on the sound side. All are very sharp (probably due to the shrinkage), with a reather "plastic" sound. Anyway, such slow hardening resin is a real pain in the neck to work with in such silicone moulds. Won't do it again.
Some were asking how would it look with a transparent nose flute, super-cool or like wearing a medical mask on the face... Maybe a good flute to teach nose flute playing? Well, you are the judge:
On the same topic :
- Moulding and Casting - Part 1: hard silicone
- Moulding and Casting - Part 2: casting urethane
- Moulding and Casting - Part 3: low temp alloys
- Moulding and Casting - Part 4: soft silicone
- Moulding and Casting - Part 5: casting Acrylic