Chalkboard Tips

How to Test a Surface for Erasability

Cestari Liquid Chalk Pens are designed to be erasable on non-porous surfaces such as stainless steel, galvanized tin, ceramic, glass, mirrors, and vinyl chalkboard labels.

They will work as permanent markers on porous surfaces such as paper, cardboard, unsealed slate blackboards, wood, and painted surfaces.

If you are unsure how porous the surface is, we HIGHLY recommend that you test how the markers interact with the surface first – before writing on it.

To test, follow these easy steps:

  1. Find an inconspicuous area on the surface to test your markers. A small corner, or the underside of the material is perfect.
  2. Place a small dot or line on the surface.
  3. Repeat with each new color marker you are planning to use, even if you’ve tested a different color previously as different inks can respond differently with each surface.
  4. Let the ink dry for 24-48 hours, to give it time to “cure” and see how the surface reacts with the ink. After the ink is thoroughly dry, dampen a microfiber cloth, and wipe over the writing to erase it. If shadows are left, add a spot of dish liquid.

    How to Seal a Chalkboard

    Most slate chalkboards are porous, and the ink from chalk markers will soak in and become permanent.  If you’d like to be able to reuse your chalkboards, you’ll want to seal them first. 


    The first decision is whether you want a matte (flat) finish or a shiny surface.  There are sealers for either preference.

    The next choice is whether you want a spray or a brush on finish.  Unless you are very careful, a brush on finish may go on unevenly, so most crafters get the best results with spray-on sealers.


    Each brand will have its own instructions, so be sure to follow them, but as a general rule, this is how it’s done:

    • Clean and dry the surface thoroughly.
    • Spray the sealer on the chalkboard, using an even back and forth motion.
    • Allow to the spray to dry.
    • Repeat 2 more times for 3 coats in total.
    • After it’s dry, check the surface by placing a dot with your chalk pen in the corner, allowing it to dry for 24-48 before wiping it off.  If it doesn’t erase easily with a damp cloth, apply 3 more coats of sealant, as described above.

      Some sealants to look for are Krylon Crystal Clear Acrylic Spray (shiny),  Aleene's Spray Acrylic Sealer Matte Finish, and Mod Podge Matte Clear Acrylic Sealer.

      Copyright 2021, Larson MacDowell Enterprises LLC