by Ron Joseph
Cleaning an Airless Paint Sprayer
Q: When using elastomeric products, do I still clean my sprayer as if I had just used latex?
And, if I spray oil paint through my airless, do I clean it with thinner, and leave the rig loaded with thinner?
A: Anytime you change from one coating to another you should clean the fluid hose and all surfaces that come into contact with the coating. Please bear in mind that not all paints and coatings are compatible with each other. If two incompatible coatings come into contact with each other inside the hose or fluid passages of the sprayer, you can build up thick or even solid particles that can ruin the sprayer. For this situation I strongly suggest that you clean the equipment between coatings.
If you are using a paint that does not cure inside the hose (and fluid surfaces) you do not need to clean them from one day to the next. The same comment applies if the paint solids do not settle in the hose over the period during which you are using the sprayer. Alternatively, you can flush the system and leave surplus thinner in the equipment; however, you should always insure that the spray gun tip is not blocked or plugged with solid paint. Also insure that all threaded parts are properly clean of dry paint
If you use latex paint on one day and solvent-based paint ("oil paint") the next, you must flush the system with water (to remove the latex) and then with solvents (thinners) before introducing the solvent-based paint. I recently saw a situation in which a painter changed from latex to solvent-based paint. Although he first used water to flush out the system, there must have been some remaining latex paint in the hose, before he flushed with solvent. When he introduced the solvent based paint everything in the hose plugged up. I suggest, therefore, that you do not introduce the solvent-based paint until you are absolutely sure that all the latex paint has been cleaned out of the system.
Finally, I cannot stress strongly enough the potential dangers of improperly using airless sprayers. Please carefully read the users manual and follow all the instructions that are relevant to your application.