My Glass Got Scum, How Come ?

Randy W · Post by **Randy W** » Thu Jan 08, 2004 10:57 am

Trying to use up some of my broken pot melt stock, I thought I'd incorproate it into a bowl ala Marty K. I cut the pot melt into strips then filled in around them with 1/4" black strips on edge. (all Spectrum 96 COE glass) Then I flipped everything over and fired.
The next day I ground it round, sandblasted, scrubbed very well with soap and water, dried, sprayed with borax solution, then re-fired up to 1450Â° and held for 10 minutes.
In an area of about 3" X 8" I got this blotchy scum on the surface. I tried #0000 steel wool and it wouldn't come off.
Any ideas what caused this? I suppose I'm gonna have to sand blast and re-fire again. What would happen if I didn't use borax spray and just fired the sand blasted surface? I have used the solution from the same bottle before and didn't have a problem.

http://f1.pg.photos.yahoo.com/ph/74dodg ... /my_photos

Thanks, Randy

Tony Smith · Post by **Tony Smith** » Thu Jan 08, 2004 11:47 am

Randy,

Why did you use borax?

Tony

Randy W · Post by **Randy W** » Thu Jan 08, 2004 12:08 pm

I THOUGHT I remember reading somewhere that if you sandblast the top surface you should use an overspray.

Andrew · Post by **Andrew** » Thu Jan 08, 2004 12:15 pm

You put the 1/4" strips on edge the "flipped the whole thing over." I assume you did this on a clear base - that's what it looks like in the pic. So am I right in assuming you glued the strips down or did you do the assembly on the board and then capped it. I've had problems with fuser's glue not burning off and leaving ugly scum.

Soap? Why'd you use soap?

Was the borax because the brown strips were non-fusible spectrum?

Tony Smith · Post by **Tony Smith** » Thu Jan 08, 2004 12:39 pm

Randy Wesner wrote:I THOUGHT I remember reading somewhere that if you sandblast the top surface you should use an overspray.

Only if you are using a non-fusible glass and you have sandblasted off devit. You shouldn't have to use borax on BE or System 96 glasses.

Tony

Cynthia · Post by **Cynthia** » Thu Jan 08, 2004 1:14 pm

That scum looks like what you get when you get superspray or borax trapped under glass...it doesn't fire up fully and clouds like that.

Is your scum on the surface or just under your clear cap. Is it clear capped? I can't really tell.

Tony, I'm confused about not using borax on Spectrum 96 or BE. I don't use borax often, but do use Superspray because I do get devit, particularly with glass that's getting fired multiple times like a pot melt obviously does. I use BE and Uro and If I don't use an overglaze on that second full fuse firing, I will get devit with certain glasses. Wouldn't I use borax in the same fashion for the same reason? Always on the surface though, and not on the back or sandwiched between glass.

Tony Smith · Post by **Tony Smith** » Thu Jan 08, 2004 1:32 pm

agreed, but why use borax if your glass doesn't have a devit problem? After sandblasting a combing or pot melt, you should be able to refire without getting any devit... and borax is prone to water spots which can look pretty ugly.

Tony

Barbara Muth · Post by **Barbara Muth** » Thu Jan 08, 2004 4:30 pm

Randy, I can't say much about your clouds, not having used borax or other anti-devit sprays, but I gotta tell you that I really liked your composition. Nice way to use a pot melt!

barbara

Nancy Juhasz · Post by **Nancy Juhasz** » Fri Jan 09, 2004 10:11 am

Randy, I have never never had any luck with Borax solution. I get the same nasty scum that you got. Like some of the others have said try it without the Borax. I do know it is just on the very surface because since I don't have a sandblasting set-up I used etching cream on a piece. I left it set on for quite a while and did it a couple of times. The scum was gone when I slumped this blank into a bowl mold. I didn't get a nice shinny surface it was more of a mat finish but not an etched finish. Good luck with the piece. Very nice composition.

jolly · Post by **jolly** » Fri Jan 09, 2004 8:23 pm

I also used to get scum occasionally but never do now. In my case, I had used too much borax and it did not all go into solution. So if I would shake the spay bottle before I sprayed, some of the undissolved borax would land on the glass (float) and give me scum. Now I let the borax dissolve and then pour off the clear solution (without shaking). I also add a drop of dishsoap to avoid the water spot problem. -Jolly

Tyler Frisby · Post by **Tyler Frisby** » Thu Feb 05, 2004 2:27 pm

Wowers I love that piece, did you just cut Pot melt in a tile saw then layed it down in along with the other slices of black or did you cold workem first.
Just a curious mind, again I

that piece. Great style.

Tyler

WarmGlass.com

My Glass Got Scum, How Come ?

My Glass Got Scum, How Come ?

two things

borax scum