Handprint Slumping

Yona · Post by **Yona** » Tue Dec 02, 2003 9:44 pm

My daughter's grade school teacher has a great idea to make glass handprints of the kids for x-mas gifts--except no one at our school currently knows how to do this! As the most experienced of the non experienced (I have a some knowledge of fusing and slumping...no experience with mold making) I have been nominated to give it a try....I'm hoping for some kind soul to walk through this step by step with me?

I was thinking of using plaster of paris since we have no need of keeping the mold and they will be very small.....but,

will it crack?
does it need to be prefired?
should there be holes in it? Won't the glass drip through?
would it be better to do a clay print then pour in plaster and use that for a slumping mold? In which case could it be P of P or should it be the plaster/silica mixture? (this would make a negative hand in glass=more work)

Any tips would be so very appreciated!
thanks
--YO

Tony Serviente · Post by **Tony Serviente** » Tue Dec 02, 2003 10:07 pm

I've done something similar Yona, and had greatest success with the following. Start with trays about 8 x 8" and 2" deep. These can either be hot glued up with cardboard, or can be inexpensive plastic storage containers. I prefer hot gluing as I don't need that many containers gathering dust. If you hot glue, line the forms with plastic wrap. Mix up plaster of paris and pour in enough to almost fill the tray. When it starts to set, the hand prints are made, stressing to the kids that they should spread their fingers wide. After the plaster is set, I remove the molds from the trays so it dries faster, and I usually park the molds where it is very warm, like under one of my kilns. After a few days I put 8 x 8" squares of glass over the molds, then put them in a kiln, slowly ramp up, pausing at 200 until obvious outgassing has stopped, then again at about 700, then up to well past usual slump temps, as high as 1475. The molds will crack, the glass may be a little funky, the slump will not completely fill the mold, but you'll have hand prints in glass that the kids will love. There are many other ways that a project like this could be done, but this is fast and inexpensive.

Kitty · Post by **Kitty** » Tue Dec 02, 2003 10:07 pm

i think this is too complicated to carry off in the next 2 weeks.

Mira · Post by **Mira** » Tue Dec 02, 2003 11:29 pm

Probably too complicated to pull off in a few weeks, but Glass Craft's most recent edition has a full step-by-step article re: box casting that is perfect for this type of project. I plan to do my neice and nephew's prints this way.

Good Luck!!

Mira

Haydo · Post by **Haydo** » Wed Dec 03, 2003 9:23 am

You could try a thick coat of kiln wash spread over fibre paper. The imprint will be low profile thereby allowing more difinition when soaking at high temps and also allow gases/vapour to escape(re- paper)
I've been mucking around with 10mm float panels for a series being installed at home and at our cafe. I wrote off five panels to get my twelve and am happy to say this ratio is history.- Haydo

rosanna gusler · Post by **rosanna gusler** » Wed Dec 03, 2003 9:46 am

clay will work. get some white clay low fire cheap. cut slabs off the chunk. roll them flat about 1/2" thick. mash hand print. dry between chunks of drywall to keep them flat. fire glass on the raw dry clay. no wash needed. i would hold around 200f for a couple of hours so there is no steam left in the clay to blow it up. then maybe 500f/hr to 1150. then full on to 1500 or so. hold till done. rosanna

Kevin Midgley · Post by **Kevin Midgley** » Wed Dec 03, 2003 5:37 pm

Clay is dry when you pick it up and touch your cheek with the clay and it does not feel cold. 1/2" of clay can hold a lot of explosive steam. I suggest paper clay. Kevin

rosanna gusler · Post by **rosanna gusler** » Wed Dec 03, 2003 7:55 pm

you are right, paper clay would be better. with the possible time constraints, regular clay could be made to work. rosanna

PDXBarbara · Post by **PDXBarbara** » Thu Dec 04, 2003 12:20 am

How about using thick fiber paper or blanket? Burn it out first, soak w/ rigidizer, press in the hand. Dry in kiln (cracked to let the steam escape) at 200F or so. Then take it up to 400 or 500 (I forget...someone help?)
Kiln wash if you want to. Then place your glass on the mold & slump, or fill with frit & chunks or whatever.

The thicker the fiber or blanket, the deeper your handprint will turn out... (right, Barb, duhhh).

BB

rodney · Post by **rodney** » Thu Dec 04, 2003 12:40 pm

with the RIGIDIZER that i use,,,if you put your hand in it, IT REALLY BURNS, this would be bad for bunch of kids,,or the first one anyway,,,,is there a rigidezer out there that doesnt burn, and is there a place where i can buy JUST THE FLUFFY FIBER MATERIAL, WITHOUT THE BINDER, thanks rodney

PDXBarbara · Post by **PDXBarbara** » Thu Dec 04, 2003 1:30 pm

Hi Rodney,
My rigidizer doesn't burn my cute stubby li'l fingers, though I'm sure it's less healthy than dipping my hands in olive oil.

I've been home sick for 11 days (yes, I've started counting!). I'll check out the name of the stuff when I go back to the studio, hopefully later today for at least a little while. I bought a bucketfull of the stuff from Western Industrial Ceramics in Sherwood, OR. However, I THINK rigidizers are mostly all the same. People make their own brews too. It's just colloidal silica, I believe. There's lots in the old archives.

Quasi-helpfully yours,
BB

Yona · Post by **Yona** » Tue Dec 16, 2003 11:21 pm

Thanks to all for the tips....

This project was cheap and cheerful!

I did the project with plaster of paris--handprints 1/2 inch deep in plastic plant trays. Dried, kiln washed (cause first test was milky with plaster residue) then filled with frit color of their choice, topped with clear, and slowly 270/hr up to 1425!! Molds cracked but glass looks good and great detail of hands is there!

again thanks for suggestions,
--YO