[Pam S]

I'm fairly new to slab work. Any suggestions for cleaner edges would be appreciated. I'm working with Buncombe White and Highwater P-5 porcelain, both ^5-6.

[Chris Campbell]

I don't really understand your question ...
At what stage you having the problem?

[Pam S]

For example, the exposed edges of a slab built box. The edges alway look a little ratty to me. I've tried compressing them slightly with a sponge and a chamios but they never have that smooth finish that a wheel thrown piece has. Thanks.

[Chris Campbell]

One trick for smooth edges is to put dry cleaner plastic over the cut pieces ...
smooth the edges by running your fingers over them through the plastic.

Doesn't stick that way and the plastic really helps compress those edges.

You can also cut the pieces out through the plastic by pressing down rather
than slicing through ... Make sense?

[bciskepottery]

Pam S, on 16 July 2010 - 11:41 AM, said:

For example, the exposed edges of a slab built box. The edges alway look a little ratty to me. I've tried compressing them slightly with a sponge and a chamios but they never have that smooth finish that a wheel thrown piece has. Thanks.

I use a chamfer tool -- sold by Bill Van Gilder -- to clean exposed edges of slabs. The tool, which he adapted from those used by woodworkers, allows me to put a nice bevelled finish on edges at the leatherhard stage. I also use Buncombe White; the clay has kyanite in it and if you use a wet sponge you run the risk of exposing the grit in the clay because the sponge washes away the finer clay particles. A soft rib can give you a smooth look and help compress the edge or seam.

[Pam S]

Both suggestions make sense! I'll try both. Dry cleaners plastic first since I have plenty! I have noticed the exposure of grit when using a sponge on the Buncombe White. From the two responses, I think I've also been getting a bit ahead of myself in trying to smooth the edges. I've been trying to achieve this while the clay is very damp. Perhaps if I wait...

[AndyL]

You could let the slabs stiffen up to cheesehard by putting them in the sun. BTW a cleaner edge for assemblies like boxes can be made with a bevel tool. I use 45º and 30º/60º bevel cutters.

[Pam S]

I used Chris' method with dry cleaning plastic today on stiff but not leather hard clay. Worked like a charm! I can't wait to try cutting the clay with the plastic! Many thanks!!!

[Marcia Selsor]

For a crisp edge I use a sur-form tool.

[charles varni]

Pam S, on 15 July 2010 - 04:43 PM, said:

I'm fairly new to slab work. Any suggestions for cleaner edges would be appreciated. I'm working with Buncombe White and Highwater P-5 porcelain, both ^5-6.

When your piece is leather hard use a "sureform" rasp to shave the edges straight, curved or whatever. Then smooth with damp sponge. I use the small curved sureform.