Vacuuming the silicone is critical to making body-safe sex toys in silicone. We talked about the vacuum chamber last time, but what kind of vacuum pump should you use for those vacuum chambers?
As a refresher, we have to remove any air from our silicone before we do our casting pours. The TLDR version is that air in the silicone leads to bubbles in the dildo and those bubbles are places where the wee beasties like bacteria, mold, yeast, etc can grow and thrive. Check out this article for a better explanation.
Once you’ve picked out your vacuum chamber, how do you pick out your vacuum pump?
Well, the first thing to understand is how vacuum pumps are rated. Vacuum pumps are rated in CFM (cubic feet per minute) which is a measurement of how much air they can move in a given amount of time. Of course, you also want to make sure that your vacuum pump uses the correct voltage for where you are (110V for US, 220 for other parts of the world). But we’re going to focus on the CFM more than anything.
An easy rule of thumb is you need 1CFM per gallon in your vacuum chamber. If you have a 3 gallon chamber you want at least a 3 CFM pump, for a 5 gallon chamber look for a 5 CFM pump.
I wouldn’t get a chamber smaller than 3 gallons so I wouldn’t get a vacuum pump smaller than 3CFM – but I also wouldn’t get a 5 CFM vacuum pump. The reason is that you want your chamber and pump to match each other. If you pump is too small it can take too long to vacuum out your silicone. If It’s too big, the fast moving air can pull silicone up into the gauge, hose or even worse your vacuum pump and destroy them.
My goal when I am vacuuming my silicone is that I want to get to a full vacuum in 90-120 seconds. I find that this is fast enough that my silicone gets degassed with plenty of time left in the pot life, but it’s not so fast that I risk pulling silicone into my gauge/hose/pump.
How much should I spend on a vacuum pump?
You should expect to pay $100-$250 for a vacuum pump. This will get you a decent pump that will last you for years with proper maintenance. Don’t go cheap though. The last thing you want is to have your vacuum pump die half way through the vacuuming process. You’ll waste silicone and you’ll just have to buy another vacuum pump.
OK… So what kind should I get?
I’ll link a few options below, but I have a RobinAir 15310 3CFM vacuum pump (Amazon Affiliate Link). It’s been a work horse and never given me a problem. You might find some bundles on Amazon that have a chamber and vacuum pump together, but I would rather pick my parts and not be locked in to a particular chamber just because the pump came with it.
One final thing to consider is that you MUST use a vacuum pump and chamber together correctly or you will destroy them!
But that’s a topic for another day…
Best,
