Devit and Super Spray

meltdown · Post by **meltdown** » Thu Nov 13, 2003 6:42 pm

I have just removed a "sushi dish" from my kiln and this was the first time we had tried super spray....when it sprayed out of the spray bottle, it seemed to puddle in places on the glass....I tried to smooth it to no avail....then i fired it to 1450....The dish has a little scumy look in some small areas here and there...I spent alot of time making it and love it and am wondering if i have to live with the results or is there anything else I can do....I know this is devit, but i thought the super spray would take care of that..Could someone also describe to me what something looks like that has been sprayed with the super spray before being fired???? Thanks sooooo much from N.C.

Bob · Post by **Bob** » Thu Nov 13, 2003 7:18 pm

The Super Spray is a milky coloured liquid ... correct? You didn't use Clear Coat? I would suggest shaking the bottle well, pouring the milky liquid into the cap of the bottle. I use a clean artist's brush to apply a coating over the entire piece. When the Super Spray dries the entire surface should be a translucent white. Fire to full fuse and there is a good chance the existing scuminess will disappear. I have done this where there has been noticable devitrification on pieces and the result has been a lovely clear finish.

Hope this helps solve your problem.

Cheers,

Bob

Cynthia · Post by **Cynthia** » Thu Nov 13, 2003 7:23 pm

What Bob said...but I would add that Superspray doesn't mature much below 1500 (regardless of what the bottle says), especially if it's thick. Refire it to 1480 or 1500 and it should gloss back up.

Was there devit before you applied the superspray? If not, I don't think you have devit, but a milky or hazy smudge left by the superspray that wasn't fully matured.

If future applications, do as Bob describes. Use a clean soft brush and apply an even light coat that once dried will be a powdery opaque white. Brush marks are okay, puddles aren't.

meltdown · Post by **meltdown** » Thu Nov 13, 2003 8:41 pm

Thanks Cynthia and Bob....I am soooo relieved to find out I can redo it....No, it had nothing on it before because this was a first firing...Someone at one of the shops had told me that you just needed to spray it....No wonder it looks terrible...there were real puddles and we did not know what to do about it....thanks............

Marc Demian · Post by **Marc Demian** » Fri Nov 14, 2003 8:52 pm

I use superspray all the time now and feel it gives me the most consistent and professional finish. You can get it to mature as low as 1300 if you hold a long time (1 1/2 to 2 hrs). I do this succesfully when slumping someting that has steep sides and needs a long slump. Works great.

I think the best way to get a good even coat of Superspray is use an airbrush. A cheap one with an can of air works fine. If you are going to use it even once in a while it's worth the $15-20 investment. marc

steve_hiskey · Post by **steve_hiskey** » Sun Nov 16, 2003 2:02 am

You can get it to mature as low as 1300 if you hold a long time (1 1/2 to 2 hrs).

WOW! This is great news. When I work with pieces from glassblowing (and system 96), I always get devit... but if I bring the piece up to 1400+ on the slumping run, it moves way too much for bowl molds. On my last piece, I made a bowl that was about 1 inch thick at the bottom.

Patty Gray · Post by **Patty Gray** » Sun Nov 16, 2003 2:19 am

Hi Steve,

Why are you getting devit with the glassblown pieces and System 96? I never use an overglaze with System 96. Are you sure you are not using just the regular stained glass by Spectrum? What temps are you working with, etc.? What processes? Blown System 96 and fused System 96 should result with a beautiful glossy finish. ???

Patty
http://www.pattygray.com

steve_hiskey · Post by **steve_hiskey** » Fri Nov 21, 2003 12:39 am

sorry for the late reply.

Hmm... that is VERY interesting. I ALWAYS get some level of devit unless I coat the blown glass pieces.

The base glass batch is Spectrum at the Seattle Glassblowing Studio. What is your batch? The Spectrum batch is considered pretty "cheap" in the glassblowing world.

Steve

steve_hiskey · Post by **steve_hiskey** » Sun Nov 23, 2003 1:10 pm

I just finished my first test piece using the process described above.

Conclusion: my assumptions about devit were all wrong.

I did an 8in rectangle using system96 clear on the bottom and various chunks of blown glass on the top... sprayed with superspray and cooked at 1500 to flatten the blown glass chunks.

Next, I heavily scratched up 1/2 of the piece. Then I lightly brushed 1/2 of the piece with superspray... so that I had 1/4 of each type: scratch-no-spray, scratch-spray, no-scratch-spray, no-scratch-no-spray. I even put a dot of really thick superspray on the two quarters that didn't have superspray (just to see if it would be milky).

Next, I slumped it in a mold with fairly steep sides... (to see if it would flow).
200dph to 1100 hold 5min
200dph to 1300 hold 90min
9000dph to 960 hold 45
40dph to 720

result: no devit ANYWHERE... and the scratches were all gone. AND it didn't flow down the sides of the mold.
(I don't completely trust the last part in that it was a fairly small peice.)

so, my conclusion: all my devit problems at slump temperatures were because I wasn't coming up to 1300 on slumping runs. I would usually get all my slumping done below 1200.

I definitely get devit with glass blown pieces at high temps (1500-1550), but superspray easily fixes that. I believe a lot of my incorrect conclusions have come from when I flip and fire pieces, which adds a whole new variable on my ability to clean the piece.