[Michael]

Hi, I am relatively new to resin casting. Here is a tediously long lead-up to a few questions:

I am trying to cast semi natural-looking eyes for a friends dollmaking projects. I think I have worked most of the process out, but I am having some trouble with microbubbles in the finished product, and its important for the cornea part to be very clear.

I am currently using resin-obsession super-clear to figure out the workflow, but plan to try polyester or polyurethane, as soon as I can figure out which will give me the best results with the least toxicity (polyester seems to be always somewhat toxic, whereas polyurethane is either not very toxic, or else super-toxic, depending on the product, and always seems to be more sensitive to temperature and humidity). I am currently using Smooth-ON OOMOO 30 as a mold compound.

My impression is that, given the limitations of space and budget, that the most cost-effective way to eliminate bubbles, is to subject both the mold material  when creating the mold, and the resin, when casting, to a near-vacuum before pouring, and then to subject both to pressure when curing. Mixing in a vacuum would probably be even better but seems difficult to manage.

Following the common wisdom, as I have gleaned from the web, I would seem to need the following items:  
For vacuum
?  a rotary vane vacuum pump of at least 8 cfm
?  a vacuum chamber (which I can possibly make out of a sturdy steel pot)

For pressure:
? an air compressor (not sure how powerful yet)
? a pressure paint pot, which can be converted to a pressure chamber(some use this as a vacuum chamber as well)

The main drawbacks, besides cost seem to be these:
? rotary vane vacuum pumps tend to be loud, and air compressors are super loud, and I live in an apartment
? rotary vane vacuum pumps need frequent oil changes (some recommend every time it is used) –the oil is messy, needs special environmentally safe disposal, and constitutes a long-term expense that is hard to justify.

Actual questions:
I have the impression that anything as feeble as a good bicycle pump is considered useless for creating enough vacuum, as are things like water aspirator pumps–why is that, assuming the air volume was kept very small?

Are there any alternatives to a rotary vane pump? Diaphragm pumps are quiet and oil-free, but dont seem to have adequate power. Other alternatives seem very expensive (several thousand dollars).

I dont know of a good alternative to a compressor for filling a pressure chamber, am I missing out on any options?

Thanks,

-Michael

[Katherine Swift]

Hi Michael,

I dont know the answer to your first question.  Im sure its a physics answer or something similar.  They just dont work for this purpose.  🙁

If youre interested in purchasing a setup, we can get you one for approximately $500.  I dont think its that noisy, especially if youre running it during the day.  You will only run it for a couple of minutes, which hopefully wont bother your neighbors.  Send us an email directly if youre interested.

[Michael]

Thanks, I will send you an email

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