Sandblasting and
resurfacing bumpy stucco

Ask the pros- September, 2002
By Reggie Bullard



      The Doylestown (PA) Historical Society recently acquired a building, part of the exterior of which is stuccoed.  About 1950 a new cinder block addition was covered with a thick bumpy cement stucco without lath.  The original building, ca. 1824, is stone.  We would now like to create a smooth, sand-like
  finish on the stucco.  Our mason initially suggested that the bumps could be ground off and the stucco painted to be compatible with the light brown fieldstone.  He thought a grinder could be fabricated if
  none was available.  Having looked into it, he has changed his mind and says the only alternative is to remove the stucco and start over - which for us would be prohibitively expensive.  Any idea how we can otherwise
  obtain our desired result ? 
The secrets of sandblasting and resurfacing the old stucco are: 
1. The surface must have at least 90% or so of the 
paint gone and rough with open pores. 
2. You must mix an acrylic admix into the bonding coat. 
There is an old fashion way that still is used in Latin America, 
but it is too much trouble. 
We use flex-con.: 

You can use a bonding coat like they say on the bucket 
or do what we do: 
cement and sand mix with 50-50 flex-con and water 
This way you can level up the rough wall 
3. We go 50-50 flex-con and water on the finish coat, too. 
It's not cheap, but well worth the results 
4. Use at least 6 mil plastic or cardboard when covering windows, etc. 
for sandblasting. 
A tip: If you rent equipment, check EVERYTHING before you leave. 
Including, helmet, filter, hoses, etc. Bring sand. 
Make sure the filter on the air filter has been replaced recently. 
5. Use this tape for windows. etc: 

Don't ever use duct tape or you'll be cleaning glue off for weeks.

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