Preparing The Substrate
We recommend that all project use a base-board or base-board treatment. In general, how you prepare a wall for plastering depends on the surface.
Some walls will require an undercoat of American Clay Sanded Primer. A few
substrates will need a brown coat prior to plastering. Others will require only
cleaning and dusting.
How can I tell if my walls are sealed?
Sealed walls will not allow water to soak in.
Here’s a quick test:
1. Using a spray bottle, lightly spray the wall with water.
2. If water beads on the surface, your wall is sealed.
3. If the water soaks into the wall surface, it’s not sealed.
Repeat the test on several areas of the wall to make sure any sealer has been
uniformly applied.
Note: a) New Gysum drywall must always be primed
b) If ANY of the surfaces in Category III are smooth troweled or “appear
sealed” always apply American Clay Sanded Primer.
SUBSTRATE CATEGORY I
Surfaces requiring an undercoat of American Clay Sanded Primer
• Newly installed drywall and surfaces finished with joint compound
• Painted or sealed surfaces (i.e. any painted or sealed surface, including
drywall, greenboard and gypsum plasters, as well as recently repaired walls).
• Slick surfaces (i.e. smooth troweled plasters and cements and smooth or
polished stone)
• Gypsum plasters such as Structo-LiteTM or GypsoliteTM
• Blueboard, all surfaces should be primed with American Clay Sanded Primer
• ACE plaster that has been sealed
SUBSTRATE CATEGORY II
Surfaces requiring a base coat or brown coat of fibered cement, lime
plaster, or a site-based earth plaster, or drywall or brick or other sheathing
recommended by the contractor:
• Unfinished adobe, cob, or rammed earth
• Rastra® or Perform WallTM
• Foam building-form blocks—i.e. Poly-Steel
• Unsurfaced straw bale or light clay
• Aerated autoclaved concrete blocks: i.e., HebelTM block, e-creteTM
• Unsealed monolithic (poured) concrete
• Unsealed, sealed, or painted brick, concrete block or stone
SUBSTRATE CATEGORY III
Surfaces requiring only a cleaning and dusting
• Unsealed sand-finish cement stucco—Fast-WallTM and fibered cement
• Unsealed mud plasters
• Unsealed lime plaster
• Unsealed porous stone (e.g., cleft or tumbled stone) |
