Poly Vinyl Alcohol Based Liquid Masks

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Masking artwork for laser engraving, sandblasting, etc can be difficult:

  • putting on the mask
  • making sure it’s burnished around the edges
  • weeding lots of little bits afterwards
  • potentially sticky residue

And sometimes things just bleed under the tape anyway.

Another option is a liquid, paintable mask that peels or rinses off afterwards.

e.g. LaserBits LiquaMASK (now owned by Rowmark). Apparently very good, but expensive?

Suppliers:

Liquid masks are quite common in industry, and now are a big thing in the cosmetics industry too.

What Makes up a Good Liquid Mask

This patent description has some really good general info describing liquid masks for automotive painting use.

  • a solvent to carry all the components (typically water)
    • may need extra additives to remove unwanted ions (eg water hardness). e.g. EDTA, chelating agent, metal ion deactivators, water softeners, etc. Borax can be a water softener
  • a liquid carrier that aides in dispersal of the surfactant and thickener/film former (polyhydroxyl - often glycerol, sometimes mono propylene glycol. Often found in “safe” anti-freezes.)
  • a surfactant. Aids in “wetting” and “detergency”. Also helps level the fluid. Non-ionic surfactants are preferred.
  • a thickener or film former; eg xanthan gum, Poly Vinyl Alcohol (known as PVA or PVOH), or Poly Vinyl Acetate (also, and confusingly, called PVA), cellulose. Typically a polysaccharide. May want it to be “wet” or “tacky” - to absorb dust. (Borax can do that - e.g. “slimes”.)
  • drying accelerators. Ethanol (or isopropyl alcohol) are commonly used.

Approximate Proportions

  • carrier (water): 70 wt-%, pref 75-95% wt-%
  • thickener 0.5-5 wt-%; closer to 0.5-1.5 wt-%; 0.8-1.0 wt-% if xanthum gum
  • 15-20% (preferably 10-18%) glycerol or similar polyhydroxy carrier
  • surfactant, pref fatty alkanolamides: 0.01-5 wt-%, pref .1-1% wt-%

Some Recipes

Info on Some Ingredients

Meaning of Terms