Art & Inspiration Casting with resin questions

Yeah, that glue is really just solvent. You are literally solvent-welding the plastic.

It works great too, just don't get sloppy with the stuff.

It is indeed even thinner than water.

 

Ah. Slow and steady.. Thanks Matt!

Dave

 

Huh! I always thought a thin stream would make more bubbles.

 

I mix my resins by hand slow and scarping the sides of the cup and have very little in the terms of bubbles . also when adding the 2nd part pour it like a beer down the side of the cup to prevent any bubbles from forming and when I pour the mix I do it close to the mold and down a guide bar ( the stirring stick ) then it goes into the pressure pot . with some of theses reins you have to work fast as they start potting in 3-4 minutes .

 

I fooled around for a while before I even got my first good mold. I used some 2 part silicone from the hobby store just for molds. I bought the stuff for heavy undercut pieces. I couldn't get it mixed well without bubbles so I started building a vacuum chamber.

I had a plastic food storage container that was clear with a hard lid on it. I drilled the lid and epoxied a barbed fitting in it. I inherited a speedair vacuum pump from my grandfather so that part was covered.

I found cups that worked perfect with the size of my knob so I glued the knob to the bottom of the cup with hot glue. Fill the mold and place it in the vacuum chamber, watch out because it will rise big time. I throttled the pump until it settled just below the rim of the cup and let it go until it completely settles and gets smooth on the too surface. Then you can let it sit and cure.

When I cast the knob I mixed the resin well and didn't worry about bubbles. I then put the cup in the chamber and let it pull the bubbles out till it was just about cleared out. Pour that into your mold very gently and place the mold in the chamber and let it run for a while.

I can now get crystal clear knobs

The cup as a mold worked excellent because the base is wider then the top and the lip around the bottom is a good catch for when the material rises from bubbles.

I can not get glitter to stay suspended for the life of me so I am thinking about building a slightly smaller inner mold and casting a nice outer shell and then filling that with a glitter resin mix after it has hardened.

Any advice on suspending glitter??

 

Zero gravity casting.

Don't ask me how to get there though...

 

Two youtube videos plus a lot more:
https://www.youtube.com/watch?v=tj_AugEruKk
https://www.youtube.com/watch?v=RYCRuVvHmbM

Remember these are done by women who are very excited about their products.
I commend them for their work.

Nick

 

I always built closed molds, so I ran the sprue down beside the cavity and up into the bottom of the cavity. This way you didn't trap air in the mold. I used large veterinary hypodermic syringes without the needle to inject the mold, I would vacuum the resin in the hypodermic to 27 inches of mercury, inject the mold, then pressurize the mold in a paint pot at 120 psi. I used GE silicone and could get about 25 parts before the surface of the mold degraded from the plasticizers in the urethane casting resin. I later found out that a better parting compound would have netted hundreds of parts before degradation would have happened.
If you are casting a clear/translucent part, using parting spray will leave a hazy finish, so it is best not to use any.
Some have good luck with a urethane mold, but you have to use a good parting compound because any casting resin, other than silicone, will glue itself into the mold. (very bad)
I played these games for a living, for the better part of 10 years, and there are a jillion things that can bite you in the ***!
There are several types of mold making silicone, addition cure, condensation cure, moisture cure, (silicone caulk) etc. Addition cure is the type I used as the others will not cure in the presence of certain materials, some paints are one of those materials.
Don't get the bright idea to use silicone caulks, they are cheap, but they are a glue, you want something that will release easily from your master and your cast parts.

 

Freeman Pattern Supply in Cleveland OH, (I think) will have everything you might want.

Vibrating will also help clear any bubbles.

 

Thanks so much for sharing this! This'll give me value priced options for experimental glitter that I can use for this as well as adding to my pinstriping! Plus I also learned how to make an adorable ear ring easel Seriously, thanks, everyone!


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Dang! This place amazes me. So many experienced people. Thanks for all the tips.
One thing I can think to ad is how to do GRAPHIC IMAGES in resin. Print an image on rice paper. When the paper is wet out w resin, it goes clear, leaving the printed image behind. Screen printing is best for nice, opaque colors and is the essential process to do white. For low budget and one offs you can run the rice paper through a color printer. It takes a little messing around to pull it off in a printer because the paper is so thin and crumple prone. Taping the rice paper (along the leading edge only) to regular copy paper helps.
Of course, do a sample with the resin you are using to make sure whatever ink you use won't run. In some cases you can fix the ink from photo copies or screen prints by spraying the printed side with clear. The rice paper will still disappear as long as the resin can soak into the back side of the paper.