Photosensitive dental composite

[Allen Friday]

A few weeks ago I chipped a tooth. I had it repaired today by my dentist, who is always happy when I chip a tooth--I think I paid for his new set of ping irons.

Anyway, he applied a glob (technical term) of stuff (another technical term) to my tooth. I assumed it was an epoxy which would have to cure for quite a time before he could grind it down to match the old tooth. I was surprised when he pulled out a special light and the glob hardened in about 60 seconds.

That's right, he used a photosensitive dental composite. According to the Teck who was working with it, it hardens in proportion to the amount of light it receives (I drove her crazy with questions.). This got me thinking (always a dangerous thing), could this be used to make photographs? After reading all I could about the material on the net, I assume it could be used to make a plate like making line drawings on circuit boards. The dental composite may turn out to be more interesting, however, because it can be molded into any shape.

Any ideas?

 

[Robert Budding]

The light generates free radicals that get the polymerization reaction going. I'll stick with silver for photography!

 

[Akki14]

"Free radicals" nice buzzword there. Most dental stuff uses UV light to cure, as far as I'm aware.

 

[2F/2F]

Sounds remarkably like how Niepce made the world's first photograph, using bitumen of judea (asphalt, basically). I just wonder 1. if the amount of light coming through an aperture would be enough to selectively harden it, let alone in the right places, without any hardening of the wrong places, 2. what happens to the areas that receive some light, but not enough to fully harden it (in short, could it render continuous tone, or only half tone?), 3. if the undried portion will wash away cleanly, and 4. what sorts of colorants would mix with it.

Oh yeah...and 5. How much does it cost?

 

[Steve Smith]

UV cure is quite common now. Most of our screen printed graphic inks are UV cure as is the encapsulant we put around components placed on flexible polyester circuits.

To me, the most amazing use of UV cure I have seen is in the finishes applied to acoustic guitars. With traditional methods, the finish was applied then left for days or weeks to harden before polishing. With UV cure it can be sprayed, exposed to UV for a short while then polished immediately.


Steve.

 

[Akki14]

Sounds remarkably like how Niepce made the world's first photograph, using bitumen of judea (asphalt, basically). I just wonder 1. if the amount of light coming through an aperture would be enough to selectively harden it, let alone in the right places, without any hardening of the wrong places, 2. what happens to the areas that receive some light, but not enough to fully harden it (in short, could it render continuous tone, or only half tone?), 3. if the undried portion will wash away cleanly, and 4. what sorts of colorants would mix with it.

Oh yeah...and 5. How much does it cost?

Physautotypes are a bit more like Niepce although that's technically the second process he tried out. I occasionally print phyautotypes in a more modern way using violin rosin for the bitumen element. They're a cheap and "easy" process to start out with but you need fan-cooled UV light for 5-6hours (and a positive instead of a negative to contact print).

 

[Rich Ullsmith]

There are dental resins that change color when cured. The purpose of the color change is to confirm that the material is cured. The only colors I am aware of are pink and blue. Also, there is no way to arrest the process, as any of the visible wavelengths will eventually cure the material.

 

[phfitz]

"To me, the most amazing use of UV cure I have seen is in the finishes applied to acoustic guitars. With traditional methods, the finish was applied then left for days or weeks to harden before polishing. With UV cure it can be sprayed, exposed to UV for a short while then polished immediately."

BASF's 'Glasurit' line has a rather high-end polyurethane automotive clear coat in spray cans that can be buffed in 90 seconds IF you use the right UV lamp, goggles required.

Welcome to the 21th century.

 

[nworth]

I hope someone will post a list of materials and sources. They may be interesting and useful in many ways not intended.

 

[Robert Budding]

"Free radicals" nice buzzword there. Most dental stuff uses UV light to cure, as far as I'm aware.

Buzzword, or not. That's how it works. I was trained as a chemist - before I got sidetracked by finance.

http://en.wikipedia.org/wiki/Radical_polymerization

 

[Akki14]

Yes but considering what most people work with in alt processes, a few free radicals is the least of their worries usually.

 

[Dave Miller]

If they are free, I'll have some. Will they make my cyanotypes work?

 

[yellowcat]

UV curing materials have been around for a long time, I cant see dental polymer being much use in image making. you would be better off using a ready made photopolymer plate:


http://www.silverclayart.com/ppplates-instr.htm

http://www.youtube.com/watch?v=JeaLq-71hk4

 

[Aurum]

That dental epoxy is working in essentially the same way as quite a few alt-process printing methods like carbon, Gum Bichromate and Casein.
The Bichromate is the sensitiser, and causes crosslinking of the substrate when exposed to UV.
It also works with PVA kids glue if you want to try it out with cheap as chips materials

If you want a commercial epoxy like material to try out, there are epoxy adhesives that UV cure. Some designed for repairing pottery, others such as UV cured etch resist for use on copper PCB boards, Screen printing was also mentioned above as well.

Another thing you could try is UV cured body filler paste from an auto supply shop like Halfords in the UK. The UK brand Holts has one that is designed to go off in Bright sunlight. Surprisingly in the UK the standard chemical initiated 2 pack seems to sell better!!

The only downside of a lot of the commercial products, is that they are UV initiated, so once they're set off they go to completion with no intermediate level. Its all or nothing, so useful for lith type work, but may be a bit "High Contrast" in comparison to the Bichromate systems .

I am tempted at some point to try UV cured etch resist on copper board. The results could look well smart if it goes right. (But B***dy expensive if it doesn't!)

 

[Vaughn]

I don't care about the dental material, I want that UV Flashlight! While I believe that some materials need UVC to be cured, if the flashlight puts out some UVA and UVB, what a great tool for burning in platinum prints and carbon prints it might make! Need a little more exposure in the upper right hand corner? Whip out the UV Flashlight and burn that nasty corner down!

Vaughn

Just checked on the UV flashlights...they seem to produce an average range of 400 to 500, some went down to 390. So might work, but between the low power and the length of the waves, burning in might take a long while!...for >$400!