Smooth finish

Linda Denli · Post by **Linda Denli** » Tue Oct 28, 2003 9:31 am

Hi there -

I need some advice on getting a smoother finish.

I have fired a tranparent base topped with white opaque and finished with coloured designs and although the finished piece looks OK on top, the base is very rough. I have just made a dinner plate and I wouldn't want to put it onto a polished surface.

I am using Spectrum 96. Original fuse is on one eighth of an inch thick fibre paper and after fusing although the bottom takes on the grain from the paper, it is relatively smooth. The problem seems to arise after slumping - into a commercially made dinner plate mold coated with kiln wash.

Is there anything I can do to make the finish smoother or will I need to look at polishing? - something I've never tried before.

Best wishes

Linda

Brock · Post by **Brock** » Tue Oct 28, 2003 9:41 am

Two quick things . . . fire on kiln wash, less texture to begin with, and sandblast before slumping for an even smoother finish. Brock

Tony Smith · Post by **Tony Smith** » Tue Oct 28, 2003 10:08 am

Alternatively, try slumping at a lower temperature. You'll pick up much less texture from your mold. I slump System 96 at 1150Â°F (621Â°C on your side of the pond) and hold for 20 minutes. The temperature in your kiln may need to be slightly higher or slightly lower, but you get the idea...

Tony

Tony Serviente · Post by **Tony Serviente** » Tue Oct 28, 2003 10:21 am

Linda-I'm puzzled that the bottom is very rough. What is the surface of the mold like? When you're done with the slump is the glass conforming to the mold completely. I don't know what could happen in a slump with a smooth mold that would have the glass go from smooth to rough, short of an overcook with the attendant bubble issues. What I'm wondering is if the bottom is not so much rough, but uneven.

Linda Denli · Post by **Linda Denli** » Tue Oct 28, 2003 11:23 am

I've slumped two different shapes - both in new, beautifully smooth molds which I coated with about six layers of kiln wash which I smoothed by hand before using. I slumped both at 1280 and allowed to soak for 30 minutes before bringing down to 950 and then annealing in the usual way.

I'll also try Tony's idea and slump at a lower temperature next time and although I don't have my own sandblaster (yet) I think I can use the one at my local glass suppliers so will give that idea a try toas well
Thanks everybody for all the help
Best wishes

Linda

Steve Immerman · Post by **Steve Immerman** » Tue Oct 28, 2003 11:31 am

Brock wrote:Two quick things . . . fire on kiln wash, less texture to begin with, and sandblast before slumping for an even smoother finish. Brock

I agree with Brock. I think the rough texture comes from the initial firing on fiber paper, not the slump firing. I get a smoother finish with a nicely kilnwashed shelf or thinfire paper.

Steve

Luiza · Post by **Luiza** » Tue Oct 28, 2003 3:53 pm

Brock wrote:Two quick things . . . fire on kiln wash, less texture to begin with, and sandblast before slumping for an even smoother finish. Brock

Hi
IÂ´m happy to be back after a long time distant from my kilns.
It seems that IÂ´ve forgotten everything

When you say sandblast how do I now itÂ´s using sandpaper or that fantastic sanblasting machine

Good to see you
Luiza

Brock · Post by **Brock** » Tue Oct 28, 2003 3:55 pm

Sandblasting is the fantastic machine, sanding is the paper. Brock

Luiza · Post by **Luiza** » Tue Oct 28, 2003 3:58 pm

Brock wrote:Sandblasting is the fantastic machine, sanding is the paper. Brock

Thanks Brock

Lynne Chappell · Post by **Lynne Chappell** » Wed Oct 29, 2003 2:30 am

You shouldn't be picking up much texture at slumping temperatures. I've found that fiber paper doesn't leave a very nice finish on System 96.