I have been painting frescoes in a church in Northern California on and off for 7 years. Until now, we have been painting only on flat walls. Presently, we are preparing to paint the dome of the church, and I am wondering if, historically, the same plaster recipes were used in domes, ceilings, and vaults as those used on walls. Thus far, and as far as we can observe, our plastering technique has worked, and has had no adhesion problems. Now that we are moving to the dome, it occurs to us that our plaster rendering will be upside down. My plasterers, professional men, who although not familiar with the technique of fresco painting, are very knowledgeable in matters pertaining to plaster walls and ceilings. They are worried about the brown coat (arriciato), believing the mix to be too "soft," and not strong enough to properly adhere to the scratch coat, hold the painting coat, and remain in place, considering the surface in question is hanging upside down. The scratch coat (trullisatio) is being done on a very solid structure of expanded metal lath.

My plaster recipe, a very simple one, the same used by Dimitrov and Bloc, assistants to Diego Riveira:

Scratch Coat (trullisatio):
1 part lime putty
1.5 part coarse sand
1 part dry white cement

Brown Coat (Arriciato):
1 part lime putty
2 parts sand

Painting Coat (Intonaco):
1 part lime putty
1 part fine sand

Can anyone advise me, or point me to someone with knowledge of historical information on fresco painting on ceilings, vaults and domes?

I have attached two photos to this posting, but never having done this before, I'm not sure they will be visible. One photo shows some of the frescoes our workshop has recently completed. The other shows the dome, with the plasterer applying the scratch coat to the lath.

Thanks very much to all the people who have posted such interesting and useful information on this site.

Fr. Simon
Saint Gregory of Sinai Monastery