Powder Line Medium

Powder Line Medium (PLM) is the generic name for a material that compares with the commercial product “Liquid Stringer”.

This recipe shows how to make your own PLM for a fraction of the price of the commercial version.  Credit for this recipe goes to Richard La Londe who is widely credited with refining (if not originating) this technique.


  • 1/4 cup CMC
  • 2 cups water (distilled preferred but not required)


  • Boil water.
  • Add CMC, stirring in slowly to minimize clumping.
  • Stir until mixed.  There will be lots of lumps at this point – that’s okay.
  • Allow the mixture to sit and cool for 24 hours.


  • CMC is used as a food additive and is non-toxic.  This recipe can be safely prepared in your kitchen.
  • CMC consistency varies among manufacturers.  You may need to experiment if you are not getting the consistency that you want.
  • This mixture can be thinned by adding water.  It cannot be thickened by adding CMC. This is why many people choose to intentionally mix the PLM extra thick and thin as needed.


  • Mix the PLM with glass powder in a squeeze bottle.  Squeeze to apply onto sheet glass.
  • Exact ratios of powder to PLM will vary due to the inconsistent nature of CMC, the variety of powder particle sizes and more. More powder and/or PLM can always be added to adjust viscosity.
  • When firing the glass consider adding a 30 minute hold at 900°F to allow the CMC to burn completely before the glass softens significantly.


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