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Forum URL: http://www.truefresco.com/cgidir/dcforum/dcboard.cgi
Forum Name: Plaster Arts & Modern Plasters and Classic Finishes with Joe Greco
Topic ID: 74
#0, Fresco Venetian plaster
Posted by Rodon on 13-Oct-08 at 08:06 PM
Has anybody used Venetian plaster by Fresco Srl, Italy to create 3xD Murals or Fresco? Which one is most sutable: Calcherra Marmorino or Marblestone?

#1, RE: Fresco Venetian plaster
Posted by admin on 13-Oct-08 at 10:29 PM
In response to message #0
"Has anybody used Venetian plaster by Fresco Srl, Italy to create 3xD Murals or Fresco?"


it is hard to tell how "venetian plasters" would behave if being painted on while wet, since the ingredients are usually a trade secret. although every lime based plaster is made of 2 main ingredients - lime putty and sand (or marble meal) the additives that are put in for ease of application and extending of a shelf life (every manufacturer has it's own set), will shrink the painting time dramatically and may render plaster almost unpaintable in buon fresco. Either way the painting time will be very short so paintings will have to be simple and fast

Most suitable plaster for fresco is a traditional mixture of 1 part of aged slaked lime and 2 parts of fine river sand.


#2, RE: Fresco Venetian plaster
Posted by classicwalls on 13-Nov-08 at 04:58 AM
In response to message #0
I have used both products internally and externally but not for fresco work
They both absorb colours but not to any extent as they are heavy ladened with sand/aggregates not of
the superior quality as others which contain marble dust and therefore absorb the pigments much better and
for longer with little fading.

hope that helps

Maria


#3, RE: Fresco Venetian plaster
Posted by admin on 14-Nov-08 at 11:41 PM
In response to message #2
Hi Maria thank you for posting!

I would like to add that painting on plaster is different from coloring the plaster itself and for painting sand "absorbs" pigments better then marble meal/dust because plaster made with sand is naturally more absorbent since the water circulates through easier hence pulling the pigments in much stronger.

It is easier to judge the final color with pure white plaster (made with marble sand or dust) since it wont lighten as much as the one made of sand. This is perhaps the reason you had "fading" usually doing your mix 2 values down (1-2 shades darker) solves the problem.

fine sand or marble meal and dust plasters do give more polished finish however it is at the expense of faster "locking" - stropping accepting paint. It is more difficult to paint on plaster made with fine sand or marble dust. Also to really take advantage of the white-marble-like surface the one should be very precise or it will loose transparency and will look just the same as if it was painted on regular fresco plaster.

Hence at the beginning until experience and advanced understanding of actual fresco painting is gained it is wise to start working with 1part lime to 2parts river sand or a classic mix of - 5parts lime putty to 8parts of river sand (Sistine Chapel Ceiling is done on it).

PS. in 12 years painting frescoes it amounts to about 10% of my work.