We are rennovating a house and my wife wants me to put my Italian fresco workshop lessons to good use by plastering some of the interior walls with traditional lime plaster. We have not yet put up the drywall, although I've been told it can be done if I cover it with a good sealer and plastic mesh.
Does anyone have any advice or tips about plastering over drywall?

This would require a fairly high skill level, to put a coat of less than 1/4" over drywall. The plaster must be perfectly level/flat - drywall is 'wavey'. In the decorating trade, this would be called a 'level 5' finish - and in union jobs, drywallers are not called for this - they call in plasterers (OP&CMIA) - this is their job. Among plasterers, there are many that lack the finesse to accomplish this. They would prefer to start the wall with metal lath, a scratch coat, a brown coat, and a finish coat(s).

This is what I recommend to you. Either learn how to do the first two coats, or get a plasterer in to do the first two coats for you, and help you with the final. The plasterer may be willing to learn something too. This is sort of like you have been taught how to decorate and ice a cake, but not how to bake it. And just like cakes, you will hear a lot of people who think they can bake, and others who claim a mix or storebought is just the same, but until you have tasted a real cake, from a real baker, you will always know the difference.(fresh eggs, fresh flour, fresh butter, well worn oven, etc.)

You will be building a 100 year old wall - a wall that will retain its beauty for 100 years - a wall that makes you (and maybe only you) smile when you see it.

Thank you, Gary, for your reply.
Fortunately, a slightly distressed look on the walls is what we are after, so some waviness will be okay.
My intension is to put 2 coats:
1st rough coat being Lime putty, 1mm sand & white Portland Cement.
2nd coat being Lime putty & .5mm sand., mixed with pigment for a faint ocherish color
I want a textured, not smooth finish, like the intonacco layer of a fresco.
My question is: has anyone worked over drywall with plaster, and should I cover the wall with a lathe mesh, and will a fiberglass mesh work or should I use metal?

Harveyk

The fiberglass mesh is easier to work with, but a little pricey. I think you should probably use 'concrete bonder' (white glue) to wet the wall and make sure the rough coat layer will stick.

Another variation is put some color on the drywall, and then patches of wax, like furniture wax, then the finish coat in a different color, the waxed areas will flake away, given the look of an ancient, distressed look plaster wall.

If the wall is to be wavey, make sure you don't use any gloss type treatments.

Sometimes for this effect you combine plaster and drywall compound about 50/50 - much harder than drywall compound on its own but it sets faster. Nothing trowels as nicely as lime though. The drywall compound/mud is basically white glue and cheap filler.

Gary, thank you for the answer. The concrete bonder, should I apply the plaster to it while it's wet? And if so, should the drywall be sealed before applying the glue or will the glue seal it.
I'm not using any marmarino or anything that will give the wall a gloss, Just slaked lime, fine sand and portland cement (mixed in for the rough coat only). I agree with you, nothing trowels like lime, or has the look of a beautiful lime plaster wall.
If there is any other advice or tips you can give me, I would greatly appreciate it.

HarveyK

The glue should be wet, it will seal and stick. Just follow the instructions on the bottle as far as dilution, etc. The fiberglass mesh will bring your wall finish up to earthquake code - thats its main purpose.

As far as tips. The lime will give a beautiful finish, it fell out of favour with decorators for two reasons. Firstly, it needs up to year to fully cure and gain its full strength. Secondly, related to the first, it will show smudges, handprints, dust etc. Eventually, someone wants to paint it, and if they use latex or oil - thats the end of that lime wall. So the ancients, especially in dusty areas like Italy, etc., used to make the walls glossy and smooth with beeswax - they kept their beauty, but could still be wiped down, refreshed. These are the walls which look like slabs of highly polished stone.

Or the other way, is to lime wash every year to make all smell nice, kill all viruses and molds, clear the mental and physical palette. Lime wash is unique in that it doesn't suddenly fail like paint, it gradually wears away gracefully. I love the old lime walls of Mexico - sadly - disappearing rapidly.

forgot to mention - if you wax the lime wall - it can never be painted, no paint will ever stick, so make sure it is a color which fits the space.

Gary, Thanks so much for the tips. I plan to mix a little pigment with the 2nd coat of plaster and than use some lime wash to make the color uneven. But about the cement bonder. While researching it, I came across this product "Plaster Wels" from Larsen's (www.larsenproducts.com/plasterweld.htm). They call it a liquid lathe, and it is supposed to make plaster stick to anything, including drywall. Reading the instructions on the can, you are supposed to let it dry before applying the plaster. Are you familiar with this product, or is there a brand of Cement bonder that you could recommend.

Sorry I am late in replying. There are many brands, usually most areas have a 'generic' cheap one in five gallons pails, then a whole bunch of fancier ones, with all sorts of claims and higher prices. In your case, one with lots of instructions and customer support (more expensive) might be worth it. If you really want to get into it, you will be looking at the 'solids count' of the mixture, thats the expensive part, the rest is mostly water. Larsen makes an excellent product - I hear - we don't see it out here because there is so little plasterwork. I have used ACRYL 60 before, and WELDBOND white glue.

If it says to apply dry, this must work, and it would eliminate the chances of it working to the lime surface, causing a slight gloss.