LAST EDITED ON 01-Feb-02 AT 01:01 PM (PST)
 
>Ilia, have you heard of "ashgrove kemilime",
>chemical hydrated lime?
>The lime from ashgrove is only 15 bucks for the
>same quantity. How can you tell the difference?
>What would be the criterias to differenciate?

I have never used it and can not see anything apart from checking the chemical specifications on both.

The real check is the trying. Nowadays we know way too much about molecules and stuff, so we do get confused and lost in it.

According to researchers, modern techniques of slaking are far more superior to the ones used in the past (kiln temperature control, hydration, etc.) The problem is that production is commercial, oriented for builders and such. The setback for us is that "dry" lime that comes in the bag will result in a "second
generation" lime putty - which may or may not be "puttied" long enough when artist is preparing to paint. Unfortunately for the moment plants do not offer putty resulted from the slaking directly (commercially inefficient), but dry it out and put in bags. So what you get is a "second generation" putty. High calcium lime for fresco has a lot to do with proper interpenetrating of its particles with water. Improper burning (too hot, too cold) of limestone and then insufficient time allowed for slaking of resulted quick lime may cause for lime not to hydrate properly or take a long time to hydrate, hence "aging" is essential. Modern technologies allow to control these processes to high commercial/constuction standards, but do these standards work for fresco painting is anybody's guess. And until there will be funds for testing directed to fresco painting, not just stuccoing and ornamental plastering nobody will be able to say for sure if it will work.

So my advise for use of bagged lime would be mixing it with water into the paste and let it sit in the paste for as long as possible 1-2 years or at least for several months.

On the other hand if we will get too technical we may not see fresco renaissance for another hundred years. And as might as well change the profession.

So how did it work for you? How is your fresco? Can you post some images?