Cleaning an HVLP Sprayer Between Coats

[Curt Rowe]

I just ordered a HVLP unit to spray cabinets. When doing so, do I need to clean the gun between each coat assuming they're an hour or two apart? I was thinking of getting a second cup and filling it with water and spaying with it briefly and putting on the finish cup back on. I only plan to use water base finishes, paints, etc.

Thanks,
Curt

[Larry Browning]

I always use waterborne finishes and I have never found the need to clean the sprayer between coats. Heck, I have gotten to where I just leave the finish in the gun until all coats are done, even if that means leaving it over night. I have never had a single problem. The gun cleans up just fine when I'm done too.

[Prashun Patel]

A lot of wb finishes can be recoated in less than that time.

The couple times I've done it, I have not cleaned the gun. If the tip has clogged ever so slightly, spraying onto a scrap surface first got the spray going fine.

[David Eisenhauer]

I have been using an Apollo HVLP and water based finishes for years and never clean out between coats. Worst case - summer time Texas heat in an un-insulated shop- have to remember to wipe the tip off when putting the gun down between coats. I can re coat every half hour (summertime without excessive humidity), but usually wait 45 min.

David

[mreza Salav]

I use 3M PPS system and have a liner filled with water that use to clean the gun (by spraying water through it a bit) between different stains/topcoats (but not between the same finish material).

[Chris Padilla]

I've left finish in my HVLP gun for several DAYS and it was fine. Maybe I had to flick some dried on stuff from the tip with my fingernail but other than that, no problem.

Things are sealed quite well in the gun...at least in my Apollo 1000 they are.

[John TenEyck]

I use shellac and WB products only, and leave them in the gun all day, but I do clean up at the end of the day. Also, I remove the air cap between coats and soak it in solvent, and wipe the end of the needle/orifice clean. Material can and does build up on the air cap and if it's WB and it dries it's not that easy to remove, so it's easier to take preventative action.

John

[Jamie Buxton]

Like the other guys, I leave finish in my HVLP gun all day, with no ill effects.

Here's an experiment you can do when you get your new gun. Well, you can do it if your gun pressurizes the finish can, which is what most guns do. Assemble the system, but without any finish in the gun. Run the turbine to pressurize the finish can. Turn off the whole system. Wait for as long as you choose. Then do something to test if there's still pressure in the can. On many guns, that just means loosening the pressure relief valve. As you do this listen carefully for a hiss, which is telling you that the can is still pressurized. If the can is still pressurized, there's no way that outside air is getting inside the can, and there's no way that anything inside the can has been escaping. This means that you could have left finish inside the can for that long with no damage.


Okay, okay, if you're shooting finish that cures by chemical reaction -- conversion varnish, or two-component urethanes -- all bets are off.

[Ed Edwards]

Jamie
Good advice! I'm glad the question was asked. Never too old to learn.

Thanks,
Ed

[Curt Rowe]

Thanks for all the responses. It's good to hear that I can leave the gun loaded between coats. One of my goals in getting the system was to make the process easier. Woodpeckers is having a sale on their Apollo systems so I went for one.

[Jim Becker]

I do not clean out my gun with the water borne products I use (or shellac) unless I'm done for the day. The gun is "sealed" in a sense when it's idle.