DIY Textured Glass Gobos?

[TupeloTechie]

In a previous post I explored using my silhouette craft cutting machine to make vinyl gobos for LED based lekos. I've had great results, in both a Strong Neeva and Colorsource Spot. Below is a vinyl gobo in a Colorsource Spot I projected in celebration of July 4th. Ran fading between Red, White, and Blue for around 8 hours with no loss of quality.


I've recently used the machine to help etch shot glasses for opening night gifts, and the results got me thinking about using glass etched with this Armour Etch Cream to make textured glass gobos, as I've always enjoyed playing with Rosco's textured glass range, but haven't ever had the budget to use multiples. These would be for 575w Source Fours, not LED.

I'm assuming I would need some sort of special heat resistant glass? It's possible that the etching cream wouldn't even work with it, but I though someone on here might be able to point me the right way.

Thanks!

 

[derekleffew]

In 2011, some dude (one Alex Weisman, aka @icewolf08 ) did an experiment (see attached pdf) demonstrating that a 575W, 115V HPL-lamped 26° SourceFour's gate temperature rose to 611°F after fifteen minutes. In 2007, ETC stated 622°F for similar. So that's the minimum requirement of candidate glass. I suspect that etching a pattern with frosted and un-frosted areas may not yield any desired results, but I could be wrong. Looking forward to the results.

See also the threads:
https://www.controlbooth.com/threads/etc-s4-thermal-temp.34815/
https://www.controlbooth.com/threads/glass-gobos-and-360q-not-friends.23958/
In particular, this post:

...
IIRC we measured over 1,000 degrees F with a 750W lamp back in the days prior to 575W availability for this unit [360Q]. Crystal will withstand these high temps, but most gobo buyers cannot withstand the price associated with actual crystal, as it is an organic substance grown in the lab, sliced and ground to optical quality. Joel (Apollo's owner) offered crystal to several large companies when asked for a product able to handle the high temps associated with the aluminum reflector and 750W lamp combination.
Borosilicate (think Pyrex) is much less expensive than crystal for manufacturing gobos, but has a tendency to 'slump' while under intense heat. I remember inspecting a b/w glass gobo in the late 1990's returned from CBS news agency that had heated to such an extent that it began to sag in the gobo holder. Unreal.
...

 

[Kelite]

TupeloTechie- you certainly can use the etchant to produce texture on the surface of the glass, but remember if using 'shower door' glass, it is a soda lime glass which has been hardened by immersion in salt water. Really salty, really hot water, This provides a surface hardness similar to that of case hardening of steel- the chocolate coating on a Klondike bar, if you will.

Your etching may indeed work, and you might consider a source for borosilicate (Pyrex) for its exceptional expansion coefficient.

http://www.edmundoptics.com/optics/...windows/borofloat-borosilicate-windows/83378/ or similar product would suffice.

 

[Jay Ashworth]

FWIW -- and this may only apply to the Pyrex cookware -- I am told that the chemical composition of sodium borosilicate glass(ware) has changed over the years; if you're going to experiment, this might be an issue to investigate.

 

[techieman33]

FWIW -- and this may only apply to the Pyrex cookware -- I am told that the chemical composition of sodium borosilicate glass(ware) has changed over the years; if you're going to experiment, this might be an issue to investigate.

I know that the Pyrex brand has changed. It's a lot more susceptible to exploding from heat and sudden temperature changes. But if your buying borosilicate glass it should still be borosilicate glass.