Using recycled solvents? Read this.

The use of solvent recyclers can greatly reduce the need for virgin solvent purchases and waste disposal.  A solvent recycler works by using distillation, which separates volatile and nonvolatile solutions in a solvent. The solution is boiled and the vapors are condensed back into liquid in a separate tank.  The non-volatile portion of the liquid remains as a solid at the bottom of the recycler for disposal.  In a paint shop, this portion is the paint solids that will not evaporate.  

Unfortunately, water is also a volatile solution, and it will end up in the recycled solvent if the solvent to be recycled is contaminated with moisture.  This can be a problem if the solvent is to be used for thinning or flushing coatings products that contain a moisture sensitive catalyst, such as isocynates.  This is an especially large concern when 2K mixing systems are flushed with hygroscopic solvents.  Hygroscopic solvents, such as acetone, absorb moisture from the atmosphere.  Introducing any moisture into a 2K system with a moisture sensitive catalyst can result in crystyalization of the catalyst and disable the mixing unit.  When using a recycler with a hygroscopic solvent, keep in mind that the moisture content will increase each time that the solvent is recycled.  Methyl Ethyl Ketone (MEK) is not hygroscopic, so it is a better candidate for solvent recycling.   

If you are using a solvent recycler, the best practice is to use recycled solvent for equipment cleaning only.  Don’t flush 2K mixing systems with recycled solvent.  If you choose to thin coatings with recycled solvents, you may be introducing a host of incompatible and undesirable compounds into your coatings.  If you are in doubt of the purity of your recycled solvent, you can have it tested for moisture content.  

Strand’s Industrial Coatings is an authorized distributor for Becca solvent recyclers.  Spray Paint Gun Cleaners, Washers, Solvent Recyclers – BECCA (