Spraying latex paint

[woodmats]

I want to spray latex paint with a TCP gravity HVLP gun but so far with poor results. The gun has a 2.5 mm nozzle and I'm diluting the paint 20% with water but it seems to still be too thick. Floutrol does not help. This is my first attempt at spraying anything except with a rattle can so maybe I should practice on something simpler. Can I dilute the paint more? I'm using Valspar semi-gloss interior paint on top of a primed, smooth surface. Stick to brush for this kind of latex?

[jteneyck]

Do you have a little plastic filter in the gun inlet, below the cup? If so, take it out and throw it away. That might be your problem all by itself, but who knows if you don't know what the viscosity is. You should get yourself a $6 plastic #4 Ford cup and measure the viscosity. Also, download Jeff Jewitt's article on spraying paint. It will show you what the correct viscosity is for your gun/needle combination, and gives advise on spraying latex. Good luck.

John

[Woodenfish]

Floetrol is not a paint reducer. I don't think you are spraying with the right type of equipment. What is it you are working on?

[JR1]

I'm basically with John.
Flowtrol modifies how the coating behaves once it's on the surface. (Improves self leveling.) it's not a thinner it only works once the paint is on the object.

You may be over thinning; most companies suggest no more than 10% water be added.

You are actually using the wrong tool for this job. Sure HVLP will work fine but with more difficulty than an airless sprayer. What you will want if you are doing a lot is an Airless Paint sprayer ; Wagner makes a bunch of decent ones at low prices and Graco makes better at higher prices. If you are painting a few cabinets or a couple doors there is no need to consider them; but if you are doing a lot it may be worth the investment.

[woodmats]

John, I did not use the filter. I had read before that you should leave it out. You are right that I should get a #4 Ford cup so I can measure the viscosity and not just guess. I could not immediately find a source in Denver so I will get one using the web. I'm an engineer and strongly prefer to go by numbers instead of feel

I am trying to paint a cabinet with drawers and want to learn how to put on a smooth coat of paint.

JR1, when I spray, I have to move very slowly and even then, the paint does not build up much and does not flow. The result was OK but the surface was not smooth. I think Jeff Jewett in an article mentioned 20% water as the proper amount of dilution for latex paint as well as using a 2.5 mm nozzle. Maybe I should try an airless sprayer. I set up a make shift paint booth in my basement with an exhaust fan in a window and with another window open for replacement air, the airflow seems to be pretty good. I understand airless sprayers blow paint all over the place.

[JR1]

Modern airless and air assisted sprayers are fine. Not quite as good as HVLP or LVLP but not real messy. The bad over spray problem occurs with the old stile paint guns and with any attempt to spray oil paints.

[jteneyck]

An engineer is writing this. I don't know anything about the paint you are using, but SW's ProClassic latex acrylic trim paint is around 98 Krebs viscosity (IIRC) which is something like 500 seconds through a #4 Ford cup. Obviously, it's not meant for a gravity feed gun. I once sprayed it by adding 18% H2O to get the viscosity down to about 65 seconds so I could spray it. It came out OK, but not great. You fight getting enough on for it to flow out w/o it running because the rheology is screwed up from all the water, or you spray it on thin so it won't run and end up with a dimpled, spattered surface. Sound about right?

You will find it very difficult to spray typical paints with your setup. I ended up buying a pressure assisted HVLP gun and it sprays stuff up to 100 seconds w/o problems, and I'm sure I can spray even thicker stuff. So I think you have two choices. Get a new gun, or use a product that has a viscosity the gun you have can spray. If you don't want to buy a new gun, look at ML Campbell's Agualente Plus. It has a viscosity of around 35 seconds so you should be able to spray it with about a 1.5 mm N/N. If you decide to buy a new gun, I highly recommend the Qualspray AM-6008 SmartPak from Jeff Jewitt. I can spray everything from shellac to the paint I described above, with beautiful results. If you want to spray high viscosity paints exclusively, however, an airless sprayer is a better choice.

John

[woodmats]

Thanks JR1,

It would be nice to have a Graco airless sprayer but for occasional, small projects, I hesitate to spend that much money. I've been checking CL but in Denver, people are asking ridiculous prices for their stuff. You may have noticed. I had my house exterior painted last fall and I was admiring the spray gun setup they had. I have a friend who has an airless gun and I should borrow it to check it out.

[woodmats]

Thanks John,

Once I get the Ford cup, I can see better where I am with the viscosity. Even with 20% water it's still too thick for the gun. The result is a nice sheen and looks fairly smooth from a distance but when you check the surface with your hand, it has small specks all over and I have an urge to sand it. I did not yet dilute it more. I have a small compressor so I need to have a reasonable amount of paint from the gun, not having to spend 2-3 seconds in one spot for coverage.

I don't have one specific type of project that I typically do so something universal and affordable would be great. I know that I'm not very good with a brush so having a spray gun would be a great addition. The Qualspray setup looks nice and I may put it on my wishlist. I like the availability of all the different nozzle sizes.

[Sandking]

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