Here are the 5 biggest issues I see out there concerning prep work:

1 - Stop the cracks – Can you do an exterior?  Sure!  Can you do a shower?  Sure!  But you gotta stop the cracks.  So you have to know what you are doing.  Or hire someone that does.  And a very important point to bear in mind – lime does not crack by itself.  But it cannot bridge cracks. It adheres to whatever substrate it attaches to.  So when the substrate cracks the lime plaster cracks with it.  And never promise a crack free finish because if you do not actually do the substrate construction and preparation how can you guarantee the thin veneer of decorative plaster we apply will hold?  This often falls outside of our area of expertise and responsibility.

That being said, EIFS mesh and primer systems usually work pretty darn well, in my experience.

MESH AND BASECOAT

2 – Penny wise pound foolish  (AKA prep with the good stuff, you’re worth it!) – So you gotta fill a wall that has orange peel texture because you want to run a nice shiny plaster over it.  So you get out the joint compound because it’s cheap.  You skim.  Then you sand.  Then you prime.  Twice.  Then you can apply your lime plaster.  Hey but wait a minute, why didn’t you just skim with our Marmorino Classic and then do your finish right over it?  Because it’s so damn expensive you say?  But think about it -  if you skim with the good stuff you’ll already have your first coat of lime plaster on.  You’ll have the proper suction and you can do your final coats the next day.  The money you spend on materials (joint compound vs lime plaster) should be more than offset by the money you save on labor, no?

3 – Scrape don’t sand – Got some excess gunk on the walls before you start?  Or did you get some trowel lines from your first coat?  Before you throw up the giant cloud of dust with that sandpaper try breaking out a putty knife and scraping.  Less work, less dust, more better.

4 – Taping – it’s not paint – Yes it’s not paint so don’t tape right up to inside edge of where your wall meets your baseboard or crown molding or whatever you are protecting.  Otherwise you’ll bury your tape underneath your plaster and it will chip or crumble off when you remove your tape.  Allow for the thickness of the plaster material you will be using and tape away from the wall by 1/16″ or more depending on what material you are using.

NOT LIKE THIS

LIKE THIS

5 – Do not assume the people doing your prep are going to do it properly.  Unless they work for you. And then only if you know what you’re doing.  Which is debatable.