Purple Painter Problem

I’ll state up front that I’ve never used a spray gun, only used a paint brush or rattle cans.

However, I do have an old Craftsman compressor (33 gal/150 psi) & recently bought a cheap HF Purple handled HVLP spray gun because it had good reviews & was on sale.

So, we just updated our kitchen table chairs with Canadel Windsor chairs as show, except the seat was a dark maple & the back/legs were a French Country white. Our three island swivelI chairs were similar in style, but made of white oak with a polyurethane finish. My wife asked if I could paint the older chairs. Yes dear.

I completely disassembled the 3 chairs, including removal of the fan spindles which later turned out to be an experience reassembling them. I brush applied a coat of poly to the seat & then a wipe-on poly coat to finish it off. Looked great!

I attempted to spray a coat of matching white latex using the HF spray gun.

It was soon obvious that the 1.4mm (0.055”) tip was too small, so I drilled it open to 2.26 mm (0.089”), leaving only about a 0.005” wall at the tip opening. I increased the pressure from 50 psi to 65 psi. That worked better, but still the gun clogged up fast. I removed the paint filter & that helped a bit. I increased the pressure to the gun max. of 70 psi and noticed that the air pressure didn’t shut off when I released the trigger. The rod pushing the trigger back would push it only part way allowing the compressor tank to continue discharging. The tank pressure dropped down to ~ 30 psi, so I was able to do only the legs or back at a time before I had to stop to let the compressor recharge itself.

I finally finished the latex painting (2 coats) & then applied two coats of Polycrylic clear coat. Despite everything going wrong (my fault) it really did look good & the wife was happy. Mission accomplished!

Then when cleaning up and I noticed that the compressor wouldn’t fully charge for use in my work shop. Taking the head off to check on the compression I noticed that the compression ring had a section that was broken off, thereby preventing the compressor to charge properly. So I took things apart, cleaned everything & ordered a replacement cylinder sleeve kit with O-Rings. The kit should arrive next Mon – Wed.

Lesson learned the hard way. Next time, if there is one, I’ll get the correct spray gun, perhaps a HPLV.

Al, different finishes may require different guns. Your choice of finishing product can make a big difference, too...

You can't just drill the nozzle out. It doesn't work that way. Spraying latex with an HVLP gun is probably the wrong way to go. You need to buy a needle and nozzle pair, and possible a cap to increase the flow of the paint.

You can thin the paint out until it flows. You may have to do a lot more coats than if you were able to put it on straight.

Quote:

---

Originally Posted by Leo Graywacz

You can thin the paint out until it flows. You may have to do a lot more coats than if you were able to put it on straight.

---

The major caveat here is that most water borne paints and coatings cannot be thinned more than 5-10% without seriously risking the quality of the finish. Water isn't the solvent...it's just the carrier and when you add more to the finish, you're effectively spreading out the actual finish molecules. Beyond a certain point...coverage gets "not good" and dissatisfying. Minor thinning is ok, but as you note selecting the correct gun and gun configuration is very important, especially with thicker coatings.

Jim, I totally agree. Lesson learned!

Quote:

---

Originally Posted by Leo Graywacz

You can't just drill the nozzle out. It doesn't work that way. Spraying latex with an HVLP gun is probably the wrong way to go. You need to buy a needle and nozzle pair, and possible a cap to increase the flow of the paint.

You can thin the paint out until it flows. You may have to do a lot more coats than if you were able to put it on straight.

---

I agree that a suitably sized Fluid Tip of 1.8-2.5 mm would be appropriate, as indicated in the HF owner's manual, but try to buy one! The HF stores don't carry them & calling HF or Central Pneumatic Customer Service doesn't get you one either. So, my only option was to drill the hole larger in this "throw away" spray gun. It was worth the risk to me. So I did & it worked. The paint I used specifically stated on the can not to thin it, so I didn't.

After going through this I wasn't about to go buy a quality sprayer just to finish up, especially when I found out that the compressor needed repairs. If I use this HF sprayer again it'll be for inconsequential outdoor applications, like spraying weed killer. :)

Al,

I'm certainly no pro, but I have learned a few things thru experience.
The purple gun is designed to shoot oil based paint and finishes like lacquer.

That being said, it is possible to spray latex thru that 1.4mm with adequate thinning - and it takes a LOT of thinning - maybe up to 50% depending on the paint. But then you have a problem with all that water having to evaporate and effectively diluting the solids resulting in a less than desirable result and more coats to achieve a good build. I've never tried it, but I've see windshield wiper fluid demonstrated as a thinner.

I have the same gun and after messing around trying to spray WB paint, I just go with oil based paints. I think they spray very well, again with proper thinning. Biggest drawback is drying time.

If oil based paint is not available in your state and/or you don't want to use them, I recommend a gun with at least a 2.0mm tip, or experiment with the wiper fluid technique.

If spraying a lot of WB paint, I would spring for a turbine sprayer. If that's not in the budget, several models of homeowner-grade electric spray guns like Grayco will do a quite acceptable job. $65 on Amazon.

The purple HF gun can spray low viscosity products really, really well. Not latex paint, as you found out. But there are other choices you could have used, like pigmented lacquer or, one of my favorites, BIN shellac based pigmented primer. That stuff has a surprisingly low viscosity and looks beautiful after you topcoat it with clearcoat. There are choices out there; you just have to look a little harder. Another example is Duralaq, sold by BM. It's a clear WB lacquer and sprays great. It also can be tinted to any of BM's colors, and still sprays great. And for most any WB product you can thin them up to at least 20% without problems. But you also can add GF's Extender which will makes most any WB product spray a lot more easily, and you only need a few percent of that.

Spend $6 on a plastic #4 Ford viscosity cup and learn how to use it. Spraying gets pretty easy once you match the viscosity of the finish to the gun. And if you want to put a low end gun on steroids put a 3M PPS pressure cup on it. You could spray your BM Advance through that purple HF gun, or the latex you were using.

John

Appreciate the comments Robert.

The HF manual for model 67181 states that the gun can spray latex, making several references to proper cleaning with water & using the 1.8-2.5 tip set. I did not modify the nozzle, only drilled out the fluid tip to the 2.26 mm dia. (#43 drill bit). So, I really did not use the equivalent of a new tip "set". Although this did get me through the job, it wasn't a good experience, and it was my fault throughout the entire ordeal for doing a half-ass job of it. But still I got through it and the LOML is happy.

Being curious about this process I've since done some research on spray painting, your's and the other's comments are right on.

Your reference to the Graco line of spray guns hit home as they appear to be what I thought might be appropriate after researching in case I ever decide to go this route again. I recalled seeing a good line of Graco sprayers at HD a while ago, so yesterday I visited HD to review their line of these paint guns. I was disappointed to find that HD has reduced the offerings of Grayco guns, focussing on the airless models. They do run more costly than the HVLP home sprayers.

Thanks John for your comments.

One thing I hadn't mentioned above is the limited options I have for spray painting.

• I didn't want to do it outside for fear of wind drifting the paint onto the house and/or insects sampling my work.
• I also am concerned about overspray & paint residue in my garage.
• Finally, my workshop is limited in size & is adjacent to a finished basement, so I have to protect against that.

So I built a 5' cube from 1" dia x 10' long PVC pipe using side outlet corner elbows, then wrapping it with plastic sheeting, plus I made a turntable to set the chairs on. Overall this contraption worked out pretty well in my garage & the temperature remained well within painting parameters.

My compressor is in the garage and I later found out that with this arrangement lends itself to the compressor inhaling paint dust which further deteriorated the compressor ring causing the pressure to leak, etc, etc, etc. With the 50' air hose I should have set the compressor outside the garage & run the hose inside to the paint cube. Another lesson learned!

There certainly is much more to spray painting than there is with a paint brush! ;)

Just rebuilt my compressor. Had to clean it throughout & replaced the Compression Ring & O-Rings with a kit sold for this purpose. Then corrected some leaks using Windex for bubble testing. Runs like new again. I use this compressor a lot, so this made my day!