spraying latex paint

[PoorOwner]

So I am using this to spray white latex paint on moldings, 40 PSI seems to be a good pressure. I started to spray as if was like a rattle can, 8-10" away. it seem the spray dry right away, I wouldn't say it's orange peel, but the surface feels like it's got sand on it and feels like a melamine surface, so maybe that's orange peel. The semi gloss appear flat, so I know when I touch up with brush it won't look right. I thinned it with flowtrol.

Turns out I needed to spray about 3" away then the paint appear wet and self levels, but the spray pattern is small and takes a very long time, more prone to mistakes, but after drying the result is pretty good now.

Do you think it's a matter of thinning it much more so it lays down a wet edge from further away? I asked about using the HVLP gun and some people say they are not good or meant for latex. I am just working with what I got not warrant to buy an airless sprayer or anything.

 

[Thumper68]

I'm guessing that you need to thin it more.

Get yourself a viscosity cup and chart, works wonders for getting the right viscosity for spraying.

 

[bullnerd]

I use a cheap old style spray gun from sears from about 1985. Its all stainless internals, so cleaning with water is not a problem.

I adjust the viscosity by eye to resemble auto paint. Just by dipping a mixing stick in and letting it run off.

Sounds like thumper has the right idea.

Personally , Id invest in a better, non HVLP, cheap gun.

BTW, once you get it working, its really fun to spray latex.

 

[laydoubtFab]

A lot of ppl who spray latex will still run over it with a roller to add texture. I did mine with a 3/8 nap roller after spraying it with an airless and it helped considerably.

 

[shepherd]

Just finished doing a dozen plantation shutters I built, and believe it or not, came across a youtube video of a guy that used windshield washer fluid to thin the paint, and it worked great! I was too far into it to change tactics and was getting acceptable results using water, but think I'll try it next project.

 

[MoonRise]

In no particular order:

- Latex is sprayable. But you need the right spray equipment (usually latex paint is rather high-viscosity and can NOT usually be thinned 'infinitely') and technique/parameters.

See the FAQ section here about 'spraying latex paint'

http://www.fujispray.com/technical/

Or here

http://www.highlandwoodworking.com/sprayinglatexpaint.aspx

- Floetrol is 'nice', but even that is rather high viscosity for a 'little' spray gun. Floetrol is not actually a' thinner', but a "retarder" that slows down dry time and thus (may) give the paint film more time to level out or for you to apply it.

See here:

http://www.flood.com/pdf/Flood-Floetrol-Application-Guide.pdf

- an external-mix siphon-feed spray gun is a bit more difficult to dial in the parameters with. And might not even be able to 'properly' spray latex. What you have there is more like an airbrush, which are awesome tools when used for the right application.

- dry and rough paint is not quite typical orange-peel, but is still not right or acceptable as a final paint film. And as you realize, will be a complete gloss mismatch when touched up with a brush.

http://www.fujispray.com/orange-peel-help/

- no, you can NOT thin acrylic/latex paint with any liquid or in any viscosity proportions. Since I don't feel like typing out a long technical discussion about it, the short of it is if you just dump excess 'thinner' (and no, windshield washer fluid is NOT an appropriate 'thinner' for acrylic/latex paint) you end up with a 'weak' paint film and adhesion or film-durability problems down the road.

(short technical diversion: alcohol is a liquid and sort-of 'thins' down acrylic/latex paint, but it also reacts with and/or destroys the resin part of the paint. So you end up with adhesion and/or film-durability problems down the road. And most windshield washer fluid is a mix of water, methyl alcohol, and surfactants (aka soap). Not what you really want to put into some paint that you want to actually 'work'. IMNSHO. )

See here about the FAQ of thinning with excess water:

http://www.sherwin-williams.com/pai...urces/faqs/interior-product-application-faqs/

Sometimes, you just need the 'right' tool for the job. It sounds like your little external-mix siphon-feed airbrush isn't really what you need for your 'job'.

 

[MarkG]

If you don't have or don't want to purchase or rent the right spray equipment, just get a good brush and brush it. There's a technique to it, and you'll still benefit from some Floetrol, but it will look almost as good as sprayed if you do it right!

 

[theoldwizard1]

So I am using this to spray white latex paint on moldings, 40 PSI seems to be a good pressure. I started to spray as if was like a rattle can, 8-10" away. it seem the spray dry right away, I wouldn't say it's orange peel, but the surface feels like it's got sand on it and feels like a melamine surface, so maybe that's orange peel.

The "grit" is tiny paint droplets that dried in mid air and then landed on the wet paint surface. Could be from the paint being thinned to much (?)



Like any sprayed paint, multiple light coats are typically required.

 

[ssdave]

You'd be a lot better off using a HVLP and thinning just a bit so it will flow freely with the needle size and air blast you use. Technically, the HVLP doesn't end up with the thinning problems discussed in the link above, because the water evaporates away in the air blast and the paint actually goes on quite dry. It sometimes has a bit of a texture as you describe if you slow down the application rate too much so that the paint dries excessively in the air on the way to the surface. Upping the flow rate a bit till you get a good film developing is the solution to that. As you noticed with your suction gun, getting closer also works better, as the air blast doesn't dry out the paint droplets as much. However, the small flow rate makes for slow work. Much better to up the flow rate rather than decrease the working distance.

I've had very good luck spraying latex with my HVLP, with about 10 to 20% thinning with water, and a heavy application rate at about 12 to 15 inches distance. I usually use the smaller needle and nearly wide open flow control valve, and a full air blast. Coverage has been about 200 to 300 sf per gallon, and a quart pot 2/3 full lasts about 2 minutes or less, at 50% duty cycle application or so.

Just recently I painted two garage doors, in panels, flat on sawhorses in the driveway. Cleaning, thinning paint, shooting the two doors with 2/3 of a gallon or so of paint took an hour. That time included switching out 10 or 12 panels onto the sawhorses sequentially to paint them individually.

 

[PoorOwner]

My latest purchase was the Benjamin Moore advance to replace the cheap stuff I was spraying.

It sprayed without thinning and no skin formed at the tip.. Basically a lot like an oil based paint with water clean up. It looks good I still can't spray from far. So maybe try this paint with HVLP next.

 

[bullnerd]

That's cool.

I thin with water like ssdave.

Im looking at floor to ceiling built in cabinets and an island I sprayed about 15yrs ago. No signs of paint failure or thinning problems.

I hope you get it work for you.

 

[Git]

Latex type paints are hard to spray

You have to make sure your using a good 'acrylic' type paint. (acrylic is the binder versus something like vinyl which is a lot cheaper) Sherwin Williams "Pro Classic" and Benjamin Moor "Advance" are probably the most common

I used to have a FUJI 3 stage HVLP - and it just wouldn't cut it. I tried everything - thinning with Floetrol, etc, etc. I ended up buying a new rig - a HVLP gun for my compressor along with a pressure pot.

With the pressure pot, I can turn up the pressure for the fluid until I actually get paint squirting out at the tip.

Another option instead of paint if your sticking with black or white colors is General Finish Poly. I have enclosed a pic just after shooting a top in black. I really like working with it

Lastly - Sherwin Williams makes a lacquer that they will tint to match their paint colors. It is called "Kem Aqua +" I haven't had a chance to try it yet - primarily because it looks like I can only by it by the 5 gallons in my area which is going to be around $300, but I have read where some stores sell it by the gallon

 

[metal1313]

im going to be doing the same thing soon, spraying latex paint. i have a bunch of interior doors to paint, as well as some bookcases and do the wife does not want brush marks.

im looking at renting or buying a sprayer since i dont have a decent compressor. although i may be able to convince the wife to let me buy a decent compressor...

 

[bullnerd]

Good info GIT.

 

[jar944]

You need a airless setup (not a Wagner hand held). Or a conversion gun with a pressure pot.

[/URL][/IMG]


If you just want smooth un-thinned advance will lay very flat with a brush