Needing Advice about Boron Nitride

[Cindy Cook]

I have sprayed "Slide Boron Nitride" onto my stainless mold according to the company's directions, and I have tried doing 3 separate draping projects in order to create votive cups. I have had very poor results. The more I used the mold, the worse the aftermath. I have no problem with boron nitride's ability to act as a reliable releasing agent. However, the material leaves a nasty residue and rough surface all over my fused glass. Worse yet, this mess is impossible to remove! Alcohol, vinegar, soap and scrub brushes will not do the job. In fact, scrubbing can damage the glass.
1st project- I used a full fused 5 inch square (opague cranberry) twhich had been fired on lava paper.
I cleaned off the glass. Then I balanced it atop the steel mold, and draped it at 1235 degrees fahrenheit. *Since the textured side of the glass was touching the mold, the milky scum was not super obvious... though... there are lots of spots that look like mineral deposits.
2nd project- I used a full fused 5 inch square (transparent champagne) which had been fired on kiln paper.
I cleaned off the glass and repeated the steps. *The draped glass now has lots of dull areas and streaks running throughout.
3rd project- I used a full fused 6 inch square (clear with blue stringers) that had been fired on kiln wash.
I cleaned off the glass, and repeated the steps. *The draped glass is uglier than the previous!

What am I doing wrong?
I just used a belt sander to remove most of the boron. I have applied another coat. I am debating whether to spray on an additional coat. Could I have overcoated it? Should I try pre-firing the sprayed mold in my kiln, and then do my drape later on? Will doing either of these things effect the outcome? I contacted the manufacturer. I was told that the product was not intended for using with glass materials. The person suggested I ask a glass expert about this matter.

Thanks for your assistance!

[Morganica]

What's your whole schedule? If the slump is so tight on the mold that it's picking up all the separator, you may be overfiring.

And are you sure this is separator residue and not devit? "Milky scum..dull areas and streaks...rough surface..." that won't come off sounds it's not just a BN problem. You might be having devitrification issues.

Can you post some pics as well as your schedule(s)?

[ejgiebel]

Cindy,

I feel your pain. I found that Slide worked well at about 1225F, but when I used it at 1325F on my stainless steel molds for weaves, it was pretty much a roll of the dice as to whether I would end up with Slide stuck to the glass. I got the same answer from them as you did, they really make the product for the plastics industry. I'm back to using MR97, which, while a lot more expensive, doesn't leave me trying to get the Slide off the glass.

Sorry,

Ed

[JestersBaubles]

And are you sure this is separator residue and not devit? "Milky scum..dull areas and streaks...rough surface..." that won't come off sounds it's not just a BN problem. You might be having devitrification issues.

I have seen the same problem. It is not devit -- definitely a coating left by the slide.

Dana W.

[Brock]

Throw it away and use kiln wash. Too easy . . .