How Can Oil and Grease Be Removed From Plastic Pallets with Aqueous Cleaners?

I had received a question from an Ask Andy fan regarding a cleaning job to remove oil and grease from plastic pallets with a pressure washer.  He wanted to know what I thought would be the best temperature for this type of operation, with the parameter of keeping the water temperature on the low side.
When deciding on what temperature to run a process, “the best” temperature is dependent on what your needs are.  In this case, the goal was to keep the temperature low which already adjusted what was “the best” temperature could be for the application.
This cleaning job plan should include the use of a cleaner paired with a pressure washer.  Greases and oil will want to stick to plastic, making their removal with only water difficult.
As to what the best temperature would be for removing the oil and grease from the plastic, any warming of the water will increase the effectiveness of removing them from the pallets.  All chemical reactions increase in speed with increased temperature.  And while cleaning is not a chemical reaction, per se, there is a chemical interaction between the soil, the cleaner, the water and the surface that happens quicker the hotter the cleaning environment.
With this particular application, the proposed plan was to pump the solution through about 40 pressure nozzles at a pressure of 40 to 60 psi.  Foaming of the cleaner can be a problem under these conditions. Due to this potential issue, we recommend using ArmaKleen M-HP-2 at a minimum temperature of 130°F and a cleaner concentration of 10%.
If the pressure washer would be used at much higher pressures, such as 1000 to 2500 psi, we would recommend lowering the cleaner concentration down to 3%.  
ArmaKleen M-HP-2 is not the only cleaner that can be used in spray cleaning applications.  ArmaKleen M-Aero, ArmaKleen 4 in 1 Cleaner, ArmaKleen M-GP and ArmaKleen Bio 24 all are formulated to be used in spray applications.