Degassing Silicone For Better Molds & Casts

In this tutorial I explain the basics of Vacuum degassing silicone to make bubble free molds. Degassing silicone, even really low viscosity silicone, will give you much better quality molds. In a future video I will be covering degassing of Polyurethanes for casting.
Materials used in this video:
TC-5140 silicone: bjbmaterials.c...
Zip 301 Mold release: bjbmaterials.c...
TC-800 Casting Resin: bjbmaterials.c...
If you need a better degassing setup than what I am using here, Centerpointe offers an industrial scale Vacuum cart. I had access to one of these when I worked in a DFW area prototyping shop and it was magical!
learn.bjbmater...

[@mcctigerfan]

Great video and explanation. I'd add, that IF in the middle of your degas cycle your material begins to overflow your bucket, use the relief valve to let vac-off. The relief valve can help "burp" the material, in essence breaking the surface tension. You can also accomplish this via a quick "rocking" action of your degas tank or vessel. It will also help break the surface tension. A warming of the material you are vac-degassing will also lower the surface tension, helping to collapse your pour. But keep in mind, any heating of your cast system will reduce work time... but that's for another video.

[@brickintheyard]

Thank you sir! You need to join me for a joint video sometime!!

[@UnvarnishedTarnished]

Mondays usually suck so having a new video every Monday is gonna be awesome! :D

[@brickintheyard]

Excellent! Next week's video should be a more interesting topic.

[@SkeleTonHammer]

Really glad you're still here making videos, and thanks for also being so active in the comments lately. Hope you're hitting a second wind. Been watching your channel for god knows how long now, maybe 10 or 15 years? Mostly recreationally, I actually develop video games, but I like doing hands-on crafts on the side and watching this stuff has been a pleasure of mine and a cool way to keep in the loop.

[@brickintheyard]

Thanks for watching! I definitely have more time to devote to comments! Lol!

[@TheSwiip1]

Thanks for the new tutorial (series?), lines up excatly right with my silicon fabrication. Just tried my vacuum pump the first time yesterday for degasing, I then also used vacuum to get the silicone into all the corners of my 3d-printed mold. It helped a lot as the features where small and the silicon very high viscosity. Worked out very nicely in the end :)

[@brickintheyard]

3D printed molds are something I really want to get into next.

[@ValorArc_Designs]

My degassing system and pressure pot are two investments that took things to the next level. So rad to see you back!!

[@brickintheyard]

Thank you! It is good to be back! I agree completely. Those two shop tools are worth the investment and improve everything! I'll be posting about pressure casting soon!

[@HoldtSteen]

A couple of things to add. When pressure casting there are more considerations. First, you can get a long way without ever needing a vacuum setup, if you have a pressure pot. You can simply cure the silicone under pressure. That will collapse the bubbles without needing to degas them. Even with a softer silicone, where the bubbles will re-expand after the mold is removed from the pressure pot, the bubbles will collapse back down when pressure is once again applied. Only an issue with silicone under Shore A 05, or thereabouts. Second, I will recommend curing silicone under pressure if the intend is to use it with pressure casting, even if you have pulled a vacuum on it. It just ensures a mold is less likely to fail when pressure casting. Any bubbles that are caught when pouring or clinging to the surface will then be collapsed. So if the option is to get a pressure pot or a vacuum chamber for the hobby caster, I will recommend the pressure pot first, as it can replace the need for vacuum in a lot of cases. Having both myself, I often forego the vacuum chamber step when making simple molds.

[@brickintheyard]

Funny you should mention this. After I posted this video I had a long chat with Troy over at BJB about this angle on pressure casting. I'll be doing a follow up on this soon. Thanks for watching and thanks for the input!

[@theneverwas2835]

Loving this new channel my friend. Thank you.

[@brickintheyard]

Thanks for watching!

[@pilfit]

Great video, I didnt realize how big an effect the viscosity had on how much silicone expands when degassing. I would just add that vacuum degassing silicone is also critically important for any parts or items cast from silicone where sanitation is important. Anything that will be used in a medical situation, for food prep and for the more adult side of things. These micro bubbles and some of them really are nearly microscopic, can allow things to get trapped in them and not be cleaned out and even avoid many sterilization methods. those bubbles make wonderful little homes for nasty things to grow in. so if you were making say a collapsible silicone water bottle. if this was not degassed you could never be sure your actually getting it clean and using it means you could give your self food poisoning. if your making a part for a prosthetic out of silicone that would be in constant contact with the skin, again you couldnt get it fully clean and so something might start to grow in those bubbles and lead to an infection.

[@brickintheyard]

Yes! I didn't delve into the casting side of it, but un-degassed silicone for food (as well as the other applications) is bad news!!

[@LordRusty5]

Hey Mitch, not for nothing, but you need to think of hyphenating the word, 'de-gas'. When I looked at the title page for your as always cool videos, I thought you were going to talk about the French Impressionist artist - Degas ... you know as in Edgar Degas ... Just a thought from a wasted mind! LOL!!!😆😎 Anyway, I'm looking forward to your Monday videos! Welcome back, Mitch! 👏

[@brickintheyard]

Lol! Thanks John!

[@big10fan71]

Could you do a tutorial on how to build a vacuum chamber and a pressure chamber. The sizes and quality of equipment needed to do the job safely for someone who wants to build their own. Thanks for the great videos.

[@brickintheyard]

The setup I'm using here is about as DIY as I would ever recommend. Using a sturdy pot from a restaurant supply is the only "corner" I would ever cut. You can make your own lid/gasket, but it is cheaper to just buy one. As for pressure chambers, I have heard some terrible stories from customers who have made their own chambers using kitchen pressure post and almost died. One guy in Dallas would put his questionable chamber out behind a plywood shield in his backyard and then turn up the pressure. That arrangement worked until the day it didn't and fragmented. His plywood shield did save his life, so there's that. If you venture into the world of homemade pressure tanks and vacuum pots, be VERY careful.

[@chrisrogers6790]

Have had one of these for a while, but never have gotten around to using one since I was just casting things like gears and washers and such. Def. going to start using it now for the various props we are making. I take it BJB is basically the same (or comparable) stuff you were white labeling before? I would love to stick with things I am familiar with for now.

[@brickintheyard]

Most of our products were BJB. If you are looking for a specific product, let me know and I'll help you. In addition to BJB's website, you can also find their products at Fox and Superfine in Atlanta. They have other distributors, but I know Fox and Superfine well and know they carry almost exactly what we had.

[@jamiehapanowicz7999]

I have seen people use extra or old cured silicone in new moldes, especially in larger spaces of silicone. They clean it and cut it up and just add it into the new mold. I don’t know how to feel about this and have not tried it. Can you let me know what you think about this. Thanks love your content.

[@brickintheyard]

I have not used that technique, so I can't speak from experience. I saw that mentioned years ago in the Thurston James prop making book. Silicone prices have come down a lot since then so it isn't as big of a savings as it was. That said, some silicones do not bond well to old silicone, clean or not. You could run the risk of a mold that will have very low tear strength and break down quickly. Be careful and run a small test to make sure you are happy with the results before you use that technique on a critical project!

[@quissum6418]

Nothing like a BITY video on a Monday! Here’s my question: I understand that the rise and fall of the silicone is important. Should I de-gas it further after it falls, or is the rise and fall enough and I can turn off the pump immediately after the fall. Thanks.

[@brickintheyard]

There's no harm in leaving the material in the chamber after the rise and fall, but my experience is that, after that, the air is out.

[@garrrbarr]

What so you use to write on your molds with?

[@imaginationworkshopstudio]

Is there a system that can degass a 55 gallon drum of silicone or other liquids in the shop or lab?

[@brickintheyard]

I'm sure there's something like that, probably custom built.

[@imaginationworkshopstudio]

@@brickintheyard custom, huh? Then that's what we need to do. But it would be nice to know how? Plans or schematics or some idea of what we're dealing with.

[@bjbenterprises]

In our manufacturing plant, we have large vessels that degas drums of material. They are custom made. For others watching/reading: do not pull vacuum on the material's storage drum, bucket, or can. You need a vessel designed for that purpose.

[@jobione1498]

Good day, I´d like to ask a question, I have to options of vacuum chamber, 1 a 1.5-gallon pot with a 3.6-cfm pump or 2 a 3-gallon pot with a 3-cfm pump (its pump big enough?). I´ll be using TC-5110F and TC-5130F mainly, in small batches thanks for all the info on your videos.

[@brickintheyard]

@@jobione1498 both of those combinations will work, but the 3 gallon pot will take twice as long to achieve a vacuum as the one in this video. You’ll need to be extra careful degassing fast setting materials.

[@jobione1498]

@@brickintheyard thanks a lot

[@jobione1498]

It’s sad you closed your store however nice you´re making more videos I wonder if you could guide me where to buy some of the materials you had in your page, SILICONE PIGMENTS 7 COLOR FLESH TONE SET, 8 COLOR FLOCKING KIT and W.M. CREATIONS STACOLOR PALETTE FULL COLOR. And maybe make a video explaining which silicone is better for hyperrealistic sculptures thanks in advance keep up the good work

[@brickintheyard]

Fox and Superfine in Georgia has all the products we used to supply.

[@brickintheyard]

Both TC-5110F and TC-5130F are great for casting realistic skins. TC-5110F is the softer of the two. Both are available through BJB Enterprises and Fox and Superfine.

[@brandontezeno_]

Do you know if a 8 cfm pump and a 3 gallon tank would remove bubbles out of resin like in 5 minutes or less?

[@brickintheyard]

That sounds like a good combination. The pot in this video is ~2.5 gallons so that's probably more than adequate.

[@coreydixon6682]

I am new to this. Does the pump need to be 6 CFM?

[@brickintheyard]

@@coreydixon6682 that’s what I’m using here as it is a good match for my 2.5 gallon pot.

[@trappedshadow]

Hahaha you still have that box cutter. One day that guy is going to see it in one of your videos. Down with the lizard people.

[@brickintheyard]

lol!

[@shidoin5398]

Reynolds advanced materials claim to not need vacuum degassing

[@brickintheyard]

The litmus test would be pressure casting. Even water thin, low viscosity systems will trap micro bubbles that wreak havoc during pressure casting. As mentioned in the video, low viscosity systems, like TC-5110, TC-5130, and TC-5140 can be used for a lot of mold making applications without degassing, but degassing will allow for pressure casting and just better results in general. Just my opinion, but the "No Vacuum" silicones are more of a gimmick for the hobby market than anything else.