Using dental acrylics

[STYRENE-SURFER]

I have used Zap-A-Gap CA with talcum powder for awhile to fill in seams and what not, but the talc is porous and always needs 

a lick of straight CA to smooth things out. 

I found this video by Paul Budzic. https://www.youtube.com/watch?v=ZaXWFM6zbLc

Anyone using this technique? 

 

[Ace-Garageguy]

Thank you for the link!

I've been doing similar edge-filling and reinforcing for years...but using expensive aircraft-grade epoxy and microballoon that has to be mixed on a gram-scale.

My technique is slow, takes hours to cure, and is generally a real PITA.

Thanks to this video, I have a great new alternative.   

 

[Mark]

Jim Keeler used two-part dental resin many years ago to fill the engine block for a contest winning funny car build.  Later he built another car, writing step-by-step articles along the way that appeared in the old CAR MODEL Magazine.  The short block (constructed with a Revell Parts Pack engine) had a crankshaft that turned, and the pistons went up and down in the cylinders.  If I remember right, he used metal tubing for the cylinder bores and used the dental plastic to fill in around them.  He built the engine for the article car around a Jo-Han engine block that didn't need the dental plastic, but he also repeated the original build to show how he'd done the contest entry.

I messed with dental resin in the early Eighties, trying to cast parts with it.  I did get some good parts but the stuff really heated up when the mixture "kicked", and that tore up the molds.  Back then I was just trying to figure out how to do it.  The railroad and military builders already had a strong aftermarket back then, but the car guys didn't.  I probably got the idea to try the dental material from the CAR MODEL article.  I was surprised at the time that I was able to buy the stuff without having to be a dentist.  Some of the other materials and tools were "restricted", not to mention the meds, but you'd have expected that.  I thought all of the materials would have been restricted. 

The materials described in the video are called "acrylics".  The stuff I had back then certainly wasn't.  The liquid half of the material was called "styrene monomer", and probably should have had a huge skull-and-crossbones on the package.  That stuff smelled nasty, and you didn't want to be shaping it with your fingers in the way this guy was handling the new stuff in the video.  I tried the baking soda/CA glue filler a couple of times but found it hard to work with, a lot harder to shape than the surrounding plastic.  The dental resin I used was pretty much the same (harder than the surrounding plastic) so I never used it as a filler, but it did work great for bonding pieces together.  I'd use something else on top of it to do the finish work.

I've got to fix the sound on my computer and watch that video again...I didn't pick up what was going on with the clear parts.  That's something I'd be interested in... 

[Ace-Garageguy]

 

...I didn't pick up what was going on with the clear parts.  That's something I'd be interested in... 

He mentioned that he uses the dental material to make molds for vacuum-forming clear parts, as it doesn't have the grain that wood molds would have.

Plain old bondo would work quite well in that application too.

He also mentions using clear acrylic material (towards the end of the video) to repair cracks in a vac-molded canopy, and to create additional contours on clear parts.

"Styrene monomer" you mention is a large component of polyester resins (for fiberglass and the glue in bondo) and shouldn't really be inhaled or handled.

Today's dental "acrylics" are intended to be used in somebody's mouth, can even be cast in-place in the mouth under certain circumstances, and are essentially non-toxic when cured and of relatively low toxicity when wet.

Edited February 19, 2017 by Ace-Garageguy

[peteski]

Dental acrylic is a 2-part compound. One is the acrylic powder and the 2nd part is a liquid (catalist?).  But you can get the same stuff in any beauty supply store as the stuff they use for doing acrylic nails.  It even comes in different colors.

I have tried it to mold come 1:160 scale wheels/tires using open mold made form silicone rubber. I used that mold in the past with urethane resins.  I filled the mold cavities with the acrylic powder and then using eyedropper I soaked it with the liquid.  The worked - I got my molded tires but the liquid made the silicone mold swollen.  It did eventually return to its original shape, but it took a while.

Latest issue of the Finescale Modeler Magazine showed a modeler who accidentally drilled through a urethane resin part using the acrylic stuff to fill the hole.  So. it does seem useful for modeling tasks. But a word of warning - the liquid part will soften polystyrene (which might or might not be desirable).

[STYRENE-SURFER]

The only good epoxy I have is West Systems 105 resin w/205 hardener, it dries rather slow but is easier to sand when cured.

But the expense and mess along w/slow curing time drove me crazy.

Did some experimenting with Zap CA and micro balloons first then tried talc., worked much better.

once you get them mixed together it actually seems to slow down the CA from drying to fast.

The acrylic powder looked like something to try but to purchase it it looks like you have to buy a large container.

The acrylic nail stuff I was not aware of, going to try it for sure.