How to eliminate air bubbles

#jesmonite #ac100 #howtochannel #airbubble #airbubbles #mould #tips #tipsandtricks #large
Jesmonite tips and tricks series
This video shows the best methods to prevent air bubbles on the surface of your Jesmonite creations! We hope this video helps, any questions please comment below.
Team Jesmonite

[@FlorinGN]

Oh wow, the result is so clean!

[@babybikermc5046]

Hi, can I use a CNC to create a pattern on a Jasmonite sheet? Any tips to not break the Jesmonite?

[@metamour]

Hi. Which Shore Hardness did you use on that specific mould? Thanks for feedback.

[@juliegayson7947]

Thank you

[@larryfroot]

I tried degassing Jesmonite but it's viscosity proved a problem. I'd recommend as wide a surface area exposed to the vacuum as possible; it helped.

[@gerda_g]

I was wondering about that! Just got a vacuum chamber today for silicone. Was gonna test it out with Jesmonite too. What about adding retarder to the mix? Have you tried that in vacuum system? And how did the cast turn out?

[@larryfroot]

@@gerda_g I used ac 300 and it was partly successful. I did contact Jesmonite at the time who told me ac100 would be a better bet as it was the least gloopy of their range, and also works with the Jesmonite pigments better, although the difference is small. I work with heavily bas reliefed surfaces where mechanical entrapment of air is more an issue than anything else. This means I find stippling onto the mold with a stiff haired brush followed by brushing on the next layer afterwards works well for me - but the I now work exclusively in AC730 which I can't imagine degassing, unfortunately. I never did try the recommendation for AC100 although I do think it would work. AC 300 wasn't too bad in the chamber. Although the wider the chamber the better, as the greater the surface area exposed, the better. Retarder...I used it to lessen the stress as adding degassing adds time to the process. You may get better mileage re viscosity using it on AC100. It has to be noted that Jesmonite have brought out a new product that thins out AC730 - there is a small chance that it may also work with other formulas or that they will bring out a similar product for their other formulas. For silicone it works like a dream. Also, as Jesmonite is water based, if you do degass it often, keep an eye on the oil in your pump. When it turns cloudy, change it. I forget why it turns cloudy but I do recall the importance of this point! Also I have found that my vacuum chamber is an ideal storage place for my 3D printing filament! I dry it with a purpose built drier, place it in the chamber with some dessicant and degass the chamber. Water boils at a far less temperature in a vacuum than outside it, so my filament is bone dry when I use it. I wonder why something as gloopy as silicone degasses with such gusto, when AC300 was a case of looking at it trying thinking "come on..." Physics, eh? If you are working with silicone then you may be interested in fillite - it is an inexpensive filler to bulk out silicone situated away from the surface of whatever it is you are molding. David Neat has a superb blog on all matters casting and he talks (eventually) about fillite here. It really can save you a lot of money. davidneat.wordpress.com/materials/mouldmaking/silicone-rubber/recycling-and-fillingextending-silicone/ Good luck! Air entrapment can be a real headache. Hope you get yours sorted!

[@franklinacevedo7663]

@@gerda_g you will have better results with a pressure pot instead a vacuum chamber

[@michaelpearson1272]

De gasing jesmonite in a vacuum chamber is not a good idea as it is a water based resin polymer and moisture in your expensive vacuum pump can damage the motor. So definitely not an idea. I use a small dentist's vibrating table. The dentist would use to remove air bubbles from plaster teeth castings.

[@larryfroot]

@@michaelpearson1272 Yes, a vibrating table for Jesmonite would be the preferred solution. I was told that the key to safely degassing water based solutions was to change the oil as soon as it became cloudy.