Spraying Latex Paints?

[Scott Shepherd]

Spraying paint has been a weak spot in my life for a long long time. I've watched many spray and do remarkable work. The whole "thinning" issue, what to thin with, and more importantly, how much to use has confused me for years.

I bought an airbrush several years ago and I fought that thing from day one. To this day, I know I have tried 4 or 5 different paints and I have yet to get the thing to spray properly (once again, illustrating I honestly don't understand this world of spraying).

I have two things, (and by calling them things, it shows my technical knowledge), one is a gun that hooks to a compressor (normal compressor) and one that is an HVLP unit. I have painted a fair amount of latex and oil paints through the HVLP unit, but it's always been on home related stuff, so the finish doesn't have to be super slick.

Now, fast forward, I'm painting some sign blanks with both the HVLP and the other gun (tried both), and I can't seem to get a super slick surface. I had a sample someone did, and I put my next to it and the color is the same, but their blank (painted acrylic), looks like glass. Mine looks like it has the texture of an orange peel. It's fine for what I have been doing, but I sure would like to know if I need to get a different gun or what. I can't thin the paint with water, as it changes the color, which I can't have.

I also can't use oil based as I'm told the carrier for the paint is something that will crack or craze the acrylic.

Anyone got any tips to get me out of the "house painter quality" mode and more into the "automotive finish quality" with latex paint and being able to spray it?

Thanks in advance!

[Joe Pelonio]

I use the HVLP for latex all the time on acrylic. First I apply the rattle can plastic primer from Krylon. When dry, I thin the latex ever so slightly with water. It doesn't take much. You'll have to experiment, I'd say maybe 1/4 cup water for a quart of paint. Any more and you'll lighten the color. It may take two coats then depending on the color but I do get a nice smooth finish. Make sure to use a water filter though, because water will make it spit and
keep it from being even and smooth.

The airbrush is meant for airbrush paint or thinner. Regular latex is way to thick so has to be thinned a lot, so it's just as easy to mix up the airbrush paint to match (I use Createx). You can get an idea of what colors are in
what you are matching by comparing to the closest Pantone color, the pantone book shows ink mix so the proportions may not be the same but at least you know what colors it contains.

[Scott Shepherd]

Thanks Joe, unfortunately, all my experiences with the airbrush were using airbrush ready paints :)

Two things I'm not sure I'll ever understand. One is paint, the second is electricity. When I was going through my Journeyman Machinist apprenticeship program, my brother was doing the same for an electrician.

I've tried for over 20 years to understand electricity as well and it just doesn't click in my brain. I can wire some things, but it's purely through logic, not because I understand what's supposed to happen.

Same with paint.

The HVLP seems to just not atomize the paint enough. Maybe putting some water in will work. I just can't lose the color by putting in too much water (and exactly how to know how much water is too much is my problem).

[Joe Pelonio]

When you thin it, start with less than more. Then dry a sample with the hairdryer or heat gun and make sure the color is still OK. Usually though, I find that a second coat gets it back to where it should be. Have you tried adjusting the needle, and the pressure? The idea of HVLP is to allow more volume of paint at less pressure, but sometimes with thicker paints you have to increase pressure.

[Scott Shepherd]

Yes, I've turned every knob on the thing. I'm not working on a project right now, but the last one I did involved removing an existing sign and replacing it. Man, that thing was like a car finish. I have thinned the paint with water over the years for other projects, and I just never seem to nail that car like finish.

If I need the right gun, I'll buy what I need, but since I know so little, I'd hate to go buy a new gun only to find it does the same thing.

Also, with the non-HVLP gun, I get pretty much the same results. Orange peely. Now, if I could just get that job painting giant oranges, I'd be set :)

[Chris Padilla]

Scott,

I like to thin Latex with Floetrol (they have two kinds: latex and oil) and am VERY pleased with the results spraying through my Apollo 1000 HVLP sprayer.

I think two things are key for spraying Latex: correct thinning and correct nozzle, powerful sprayer. (Okay, that is 3....)

Thinning ought to get you by a less powerful gun and perhaps incorrect nozzle size...you'll just have to experiment.

My Apollo is a 4-stage turbine system that cost like a grand (about 5 years ago when I got it) so it is quite powerful and NOISY as all get out. I believe the nozzle I use is a #5 which I believe is a 2 or 2.5 mm diameter opening.

One final deal in spraying latex could be the paint quality. I like to use the cheaper stuff you get at Home Depot (Ralph Lauren, Behr, Glidden) but you might do better with pricier paints from Benjamin Moore and others.

[Joe Pelonio]

Scott,

One final deal in spraying latex could be the paint quality. I like to use the cheaper stuff you get at Home Depot (Ralph Lauren, Behr, Glidden) but you might do better with pricier paints from Benjamin Moore and others.
Good point, Chris, I have been using "American Tradition" paint with much better results than the thicker and more expensive B. Moore. For durability I top coat it with Chromatic 1-Shot Clear, that stuff is thin and sprays nicely as is.

[Chris Padilla]

Joe,

Is that one-shot oil-based? Seems to be a kind of poly...or not?

Another point with thinning latex with Floetrol--one can roll as if it were sprayed on as the Floetol extends the wet edge thereby increasing drying times thereby allowing the paint to flow more easily. I really love it and consider it a big secret to painting well with latex.

[David G Baker]

Scott,
Understanding electricity is easy if you can relate it to moving like water through plumbing. A switch is similar to a faucet. The larger the pipe/wire the more water/electricity can flow through it, etc.
Can't help with the spraying of paint, in that area I am lacking the experience and knowledge.

[Joe Pelonio]

Joe,

Is that one-shot oil-based? Seems to be a kind of poly...or not?

Another point with thinning latex with Floetrol--one can roll as if it were sprayed on as the Floetol extends the wet edge thereby increasing drying times thereby allowing the paint to flow more easily. I really love it and consider it a big secret to painting well with latex.
This one is, but they also have a waterborne version.

[Bob Rufener]

I'd have to check my hvlp manual but I believe it matches up nozzle sizes with the different coatings. Make sure you have the correct nozzle on your gun. Also, it may give information about the viscosity of the fluid. You can buy an inexpensive viscosometer for less than $10.00. What it does is measure how quickly the fluid flows out of a small hole at the bottom of the cup. The thicker the fluid, the slower the time. If it is too thick, add the appropriate thinner a small amount at a time until you get the right viscosity. This should help a lot.

[Todd Burch]

I've successfully sprayed latex with a gun, but it's a pain in the hiney. It's not like spraying automotive finishes or lacquers and such. I've also had terrible results spraying latex. I mean, REALLY bad, sandpaper-like finishes. Yuk.

So, when someone wants latex sprayed, I tell them to go away. If they are REALLY persisitent, I get out the airless sprayer and put in the fine tip and I can kick out glass finishes every time.

Todd

[Phil Hudak]

I have sprayed a lot of latex. It wasn't easy when I first started, but now it's a piece of cake after quite a bit of experimentation.

I use a gravity-fed conversion gun with a 1.9 set-up.

Thin with Floetrol and water. How much is trial and error, as it depends on the viscosity of the paint. In my case, using Dunn-Edwards paint (which has the consistency of yogurt), it goes something like this:

1) Fill a spag sauce jar (20 oz. jar?) about 2/3 with paint.

2) Add 3-4 tablespoons of Floetrol.

3) Add 2-3 tablespoons of water.

4) Shake well.

It should now be about the consistency of a fairly thin pancake batter. If not, I add Floetrol and water 2 to 1 until it is.

I used to run my mixes through a #9 Ford viscosity cup; as long as the time was under 50 seconds or so, I was good to go. I honestly don't even bother measuring anymore.

Filter the paint through a medium-mesh filter into another jar or directly into spray gun cup - do not skip running the paint through a filter...ever.

Practice your spraying on cardboard and make gun adjustments to get the correct pattern and volume.

I highly recommend the book Spray Finishing
by Andy Charron for details on how to use and adjust your spray gun - it will save a lot of experimentation time. DAMHIKT.

I used to get a lot of "dry finish" - where it felt rough and wasn't glass-smooth. I found that I wasn't opening my fluid control valve far enough which resulted in too light of a spray. You have to dump a lot of paint down to get it to flow out.

HTH,

Phil Hudak

[Scott Shepherd]

Scott,
Understanding electricity is easy if you can relate it to moving like water through plumbing. A switch is similar to a faucet. The larger the pipe/wire the more water/electricity can flow through it, etc.

David, sorry, I've been through that countless times with my brother. I've helped him wire quite a few houses. I can do some of it, but it's purely from repetition, not from understanding of it. Sadly, I think I'll leave this earth never understanding 3-way, 4-ways, volts, ohms, amps (need I continue?).

Thanks to all the others for the advice. Sounds like it's time to start with a new gun, new nozzles, and a little bit of equipment. Any recommendations for a moderately priced gun? Don't want cheap, but don't need the ferarri either.

[Joe Pelonio]

Oddly enough for small jobs I have a mini gun I picked up for $10 at a swap meet, made in China that works great. Looks just like this one, even the same color:

http://www.tapplastics.com/shop/product.php?pid=354


For larger jobs I use a Porter Cable PSH1, that was $75 or so, not expensive but actually I have tried really nice spray guns that belong to my stepfather and they don't work as well for latex.

[Phil Phelps]

[QUOTE=Scott Shepherd;The whole "thinning" issue, what to thin with, and more importantly, how much to use has confused me for years.

Sparying latex throug a HVLP or a conventional siphon gun is not the best method. An airless is used for latex, and thinning is moderate, if at all. I've sprayed latex for years using siphon guns, but my application is for the sign industry and not walls and doors. And those that recommend Floetrol as a thinner are wrong. It is not a reducer it's an extender. Added to latex enamel for example, it reduces brush drag and allows the the brush strokes to even. But if your spraying latex through a siphon gun, you'll have to water the paint by 50-60% and you'll need several coats. It can change colors on you, too.

"I bought an airbrush several years ago and I fought that thing from day one. To this day, I know I have tried 4 or 5 different paints and I have yet to get the thing to spray properly (once again, illustrating I honestly don't understand this world of spraying)."

Paints for an air brush need to be as thin as ink and is usually used for art work.

"I have two things, (and by calling them things, it shows my technical knowledge), one is a gun that hooks to a compressor (normal compressor) and one that is an HVLP unit. I have painted a fair amount of latex and oil paints through the HVLP unit, but it's always been on home related stuff, so the finish doesn't have to be super slick."

A HVLP reduces overspray by about 90-95% and allows you to use more product through the tip. Again, not really good for latex paints, although small projects are about the only thing I'll use the gun on for satisfactory results. Spraying a vertical door with watered down latex is not good idea.

"Now, fast forward, I'm painting some sign blanks with both the HVLP and the other gun (tried both), and I can't seem to get a super slick surface. I had a sample someone did, and I put my next to it and the color is the same, but their blank (painted acrylic), looks like glass. Mine looks like it has the texture of an orange peel. It's fine for what I have been doing, but I sure would like to know if I need to get a different gun or what. I can't thin the paint with water, as it changes the color, which I can't have."

If I am painting sign blanks, either acrylic or metal, and I have to use oil or latex, I'll undercoat them with Bin pigmented shellac. You'll need several light coats because the shellac just sits on the blank because of the non porous surface. Bin is an excellent undercoat and provides a tooth for the paint. If I have a choice, I'll use lacquer or a professiona product call Matthews polyurethane,( sold only at sign supply companies). Orange peel is caused by too much pressue and or heavy material. You can get a glass finish using a HVLP, but the prep is the key and perhaps several coats and hand sanding in between.

"I also can't use oil based as I'm told the carrier for the paint is something that will crack or craze the acrylic"

Not sure what you mean, but alkyd products don't harm the surface of acrylic.

" Anyone got any tips to get me out of the "house painter quality" mode and more into the "automotive finish quality" with latex paint and being able to spray it?"

You will have to experiment with spray tips and material if you continue to water down latex through a conventionl or HVLP gun.
As I said, spraying sign blanks should be done with lacquer or a polyeurathane with an accelorator for top quality results.



If you would like to investigate the poly products, give me a jingle and I'll put you in touch with someone who can find a dealer for you.
Phil

[Chris Padilla]

I wondered if Mr. Phelps would chime in. :)

Maybe I'm wrong to call Floetrol a thinner but using my HVLP with and without Floetrol makes a big difference in my experience. I'm no pro, I haven't done this for years, but I've sprayed latex on a few doors, toy chests, and cabinets and the wife and I are happy with the results. Maybe others wouldn't be. I dunno.

However, Floetrol does WONDERS for the paint when rolling or brushing it and I will always use it for that purpose.

[Scott Shepherd]

Thank you to all. Phil, I'll take you up on your offer and give you a jingle some time soon. Let's get through the holiday and I'll make contact with you after that.

Until then, have a Happy Thanksgiving.

[Phil Phelps]

I wondered if Mr. Phelps would chime in. :)

Maybe I'm wrong to call Floetrol a thinner but using my HVLP with and without Floetrol makes a big difference in my experience. I'm no pro, I haven't done this for years, but I've sprayed latex on a few doors, toy chests, and cabinets and the wife and I are happy with the results. Maybe others wouldn't be. I dunno.

However, Floetrol does WONDERS for the paint when rolling or brushing it and I will always use it for that purpose.
.... when it didn't work like one. It's been a while, but I think it actually tells you it isn't a reducer on the label. You're dead on about rolling and brushing. If I'm brushing latex, I've got Floetrol.

[Phil Phelps]

Thank you to all. Phil, I'll take you up on your offer and give you a jingle some time soon. Let's get through the holiday and I'll make contact with you after that.

Until then, have a Happy Thanksgiving.
... here is a bonus with the Matthews product. Think of a color on a chart somewhere. I don't care if it's Sears, Pratt & Lambert, or what ever, they have it formulated for a dead on match. Not close, dead on.