Keeping stack whites fresh and grinding

[miller]

George

I received the stack white cakes.

1) They seem to be still wet inside the vacuum packs. Can they be mulled in this state or dried before?

2) What is the state to preserve tham in - wet as they are or dried ? (Vaccum sealing machines are prohibitivley expensive.)

miller

[George O'Hanlon]

Although we dry the stack process lead white cakes in a low temperature oven at 40º C for 72 hours, they still retain a small amount of moisture in their centers. The small amount of moisture in the cakes do not pose a problem when grinding them in oil. Lead white has such great affinity for oil that the moisture is exuded upon mixing with the oil.

If you find the moisture objectionable, you can dry the lead white by crushing the cake and spreading the powder in a thin layer in a pan and exposing to light and heat for a period of several days.

There is no need to preserve the cakes in vacuum-sealed containers. We package the cakes in vacuum-sealed plastic to prevent their form from disintegrating during shipping. We do not want the lead white powder flying all over the place.

[miller]

Thanks.

[Kenneth Freed]

My stack cakes had a bit more moisture than that but as you state, it caused no problem. When pulverizing the cakes with a muller, the water sort of exited the pigment and I took a Bounty paper towel and eliminated it prior to mixing with oil.

Incidentally, those cakes are incredible. I currently use my stack white for special areas in the painting. I wish I had enough cheese to use the stack white for every application. It is one of the great research and development projects for artists in the last 50 years.

[ 12. December 2009, 06:01: Message edited by: Kenneth Freed ]

[miller]

I'm actaully using it to emulate old lead ground on copper. but will of course use it as regular white. I purchased pale grinders old for the purpose too.

George, so keeping unground stacks in a dried state for a long time does not make them go bad? am i correct?

[ 19. November 2009, 06:07: Message edited by: miller ]

[George O'Hanlon]

No, the stack process lead white cakes do not go bad. They were never intended to remain in a moist state, but since we cannot rid them of all moisture (unless we use vacuum ovens), they retain some moisture.

[George O'Hanlon]

Originally posted by Kenneth Freed:
It is one of the great research and development projects for artists in the last 50 years.

Thanks, Kenneth.