Adventures in HVLP spraying


My wonderful wife has selected the next project for me to work on after finishing the laundry room and Im excited to get started on it.  However – I wasn’t entirely happy with how the finish on the cabinets came out in the laundry room.  I had sprayed latex paint with my HVLP gun after having thinned it with Floetrol.  A trick I had used before successfully in painting a dresser we redid for our son.  However – the gun behaved oddly when painting.  The spray wasn’t consistent and it didn’t appear to be fully atomizing the paint.  The result was an orange peel like finish.  Then – because it was latex – I had to topcoat the paint with a water based urethane which means you’re signing yourself up for visible brush strokes.  In the end, I was happy with the final product, but not thrilled.

So I spent some time trying to figure out where I was going wrong.  Last year I did builtins in the loft and had painted them using Shermin Williams Pro Classic oil based trim paint.  I had once again used the same HVLP gun and the results were really good.  The paint went on smoothly and the end finish was smooth.  The fact that I had used that paint was pure coincidence.  When we bought this house the previous owners left the paint in the basement and my wife wanted to match the same color used on the molding for the builtins so it just sort of worked out.  The one downside to spraying this paint (or using it in general) was that it had that awful oil based paint smell.  On top of that, I despise cleaning up tools after using oil based paint.  I try my best to use the right protection when doing so but using all of those chemicals never sits well with me.  So I set myself on a mission to find a means to finish wood with paint that gave me the same result as oil based paint, but wasn’t oil based paint.

Fast forward to the laundry room project and I ended up using latex based paint.  Like I said, the end result wasn’t what I wanted and I could tell that the latex just wasn’t flowing the gun the way it should.  So I did a ton of research and found out that latex based paint just wasn’t designed for HVLP guns.  Its just too thick to work properly and to get it to work properly you’d likely have to thin it down to a point where the paint wasn’t working the way it should.  It seemed that to spray latex based paint most folks were using airless sprayers.  After looking at those for awhile, I settled on the idea that they were really designed for commercial work and that for smaller projects they really didn’t make much sense to use.  So I spent more time reading articles from folks who had been successful in spraying latex out of a HVLP gun.  After more research I found that the HVLP gun I had used a 1.8mm spray cap and needle.  Most folks that were spraying latex were doing so with a much larger tip – typically something about 2.2mm.  So I went to Amazon and found a reasonably priced HVLP gun with a 2.5mm tip.  I ended up getting this one.  The gun seems solid and I was anxious to use it to spray some latex.  So I hooked it up, thinned some latex paint with Floetrol (about 10%), and started spraying some samples.  The paint flowed through the new gun much better than it did in my previous gun, but the end results after the paint had dried were still not what I wanted.  Looking closely I could see smaller spatter marks in the paint.  It was much less noticeable then before, but it still wasn’t what I wanted.

Disappointed, I gave up for a day or two and spent some more time thinking about the project.  My original reason for wanting to use latex was that it was commonly available, east to color, and cheap.  However, I had forgotten that using latex meant I would need to urethane all the wood since latex isn’t a good top coat.  That just meant more work for me in the end.  So back to the google I went to see what others used to paint cabinets and furniture.  It seemed like most folks who were doing so professionally used a lacquer based paint.  So I went off to Shermin Williams to talk to them about getting some lacquer.  After much discussion with the folks at the store, I determined that I did not actually want lacquer.  Lacquer is solvent based meaning its nasty to work with, smells worse than oil based paint, and is extremely toxic.  They said that they don’t even carry any lacquer based paint in the store and its usually reserved for professional furniture and cabinet shops (which alas, I am not (yet!)).  So after talking with them some more, they had a couple of alternatives for me.  First was a waterborne 100% acrylic paint.  They claimed that it would provide a sufficient top coat to not need to be sealed and was common to be sprayed out of a HVLP gun.  That sounded good, but the next coating he suggested sounded even more intriguing.  It was Shermin Williams water based urethane trim enamel…

They said it was a newer product, an awesome top coat, little to no odor, sprayed well without thinning, and could be tinted to any color.  I was sold.  I bought a quart of it to try and rushed home to try it out.  I first tried it in my original 1.8mm HVLP gun and it just seemed like the it wasn’t flowing correctly.  The paint wasn’t spitting, but it wasn’t coming out at nearly the rate I hoped it would even with the feed needle backed all the way out.  Despite this, I sprayed a sample and let it dry.  The results were not what I wanted…

Bumpy, bumpy, bumpy.  I was annoyed.  So I went to bed to sleep on it some more.  The next day I tried two more sample sprays and had abysmal results.  Both guns acted like garbage and spit paint all over the place.  I didn’t even get to spraying the second sample before I gave up.  So back to google I went to try and sort out where I was going wrong.  I first tried to tackle the guns spitting.  After more reading the most likely cause sounded like the spray tip was loose.  Most folks recommended really tightening them down with a wrench before spraying which was a change from my normal finger tighten maneuver.  Turned out that was my problem (sigh).  So now my guns were working correctly but I still couldn’t get the finish I wanted.  After even more reading – many folks suggested thinning water borne finishes with straight water – up to 10%.  I had been using Floetrol to thin the paint thinking it was better than water and would help both with flow and the paint settling down.  Having nothing to lose at this point, I tried it out.

It worked.  It worked brilliantly.  I was amazed at how much better the paint flowed from the gun and how smooth the finish was.  Its so hard to get a good picture of a finish, but heres one.  You can see the grain through the paint and no bumps at all…

I am thrilled!  The finish has the sheen I want (satin) and should be a sufficient top coat.  My lesson learned here is to just start with the basics.  Learning how to use the guns properly, and then start with the most basic kind of thinning.

Now I can start figuring out how to finish the next piece of the project.  More to come soon!


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