I attemp to spray Latex paint in one of my project, do I need to thin out the paint. Thank you.vn.
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Replies
I have successfully sprayed latex paint and yes I thinned it with water. I used a conventional cup-type gun. This type of spray gun will not shoot the heavy latex without thinning. On one piece, I then top-coated with a water based clear coat that allowed me to rub out the finish using pads and rubbing compound.
I have also sprayed latex without thinning using an airless rig. Of course, I was aiming at my house.
I do not know what happens to the durability of latex that has been thinned. Perhaps someone else will chime in. Or, you could always ask at a full service paint store. They "ought" to know.
Yes, thinning out the latex does make it easier to spray out with just about anything other than an air-less set up - which is designed to spray unreduced latex. However, thinning also makes it easier to leave runs and sags.
I would recommend that you first get some latex conditioner, such as Floetrol, and add that first. Then thin it a little bit with water. The Floetrol will allow you to spray the latex with less water thinning and it'll make the latex flow out much, much better. I would try out the latex on a piece of scrap. First shoot some with just the Floetrol in it. Then, if you want it thinned more, add some water until you're happy with it. You will get the best results using no more water than absolutely necessary to make it spray decently.
Regards,
Kevin
I agree with all of the suggestions so far. In addition, you might want to consider using denatured alcohol instead of water, as the thinner. It will have just about the same effect on the spray-consistency, but it will speed the drying time of the finished coating.
Vast projects should not be founded on half vast ideas.
In addition, you might want to consider using denatured alcohol instead of water, as the thinner. It will have just about the same effect on the spray-consistency, but it will speed the drying time of the finished coating.
:::makes mental note:::
That's a new one to me. I'll have to try that. I wonder if Acetone would work too. It is essentially a synthetic alcohol.
Regards,
Kevin
To be a bit pedantic, acetone is not a "synthetic alcohol", it is a ketone - a different oxygen containing hydrocarbon. It has different solubilities than methanol and different toxicology. Most important, take respiratory precautions with all of these organic solvents and beware explosion.
For the record, I thin latex for spraying with water with pretty good results. I use an cheap old fashioned spray gun.
Edited 6/27/2003 1:27:22 AM ET by telemiketoo
(I'm the guy that recomended the use of alcohol as a thinner.)
I agree 200% with the comments concerning proper respiratory precautions when using ANY solvent -- especially when using it as a thinner in a spray application.
If you don't have the right mask, and don't want to spend the money, then you should strictly limit your use of the spray apparatus to outdoors, on breezy days, and you should stand upwind. Even a low concentration of alcohol in your breathing air can cause serious irratations of the throat (and worse).
Vast projects should not be founded on half vast ideas.
To be a bit pedantic, Acetone is commercially produced in one of two ways. 1. As a product of bacteriological fermentation (sound familiar?) or, 2. produced from isopropyl alcohol which is produced synthetically from propylene obtained in the cracking of petroleum. None of which make it a true alcohol, though.
Interestingly enough, one of the most important derivatives of Acetone is the material known as Diacetone Alcohol, which is both a Ketone and an Alcohol.
Methyl Ethyl Ketone (MEK) on the other hand is produced from secondary Butyl Alcohol which is produced from Butylene also found in petroleum refinery gases. And, like Acetone, is not a true alcohol.
The above information was derived from my ancient (1944) edition of Elementary Organic Chemistry of Commericial Solvent's Products by Charles Bogin.
My point in originally bringing up Acetone is that it has many properties that are similiar to or the same as Alcohol. I've found over the years that there are some situations where one can be substituted for the other and perform the same function.
Regards,
Kevin
Edited 6/27/2003 1:21:20 PM ET by Kevin
Kevin, outside of possibly being a bit pedantic, pointing out that alcohols and ketones are not the same types of material is very germane to the issue at hand. The determinative point is the solvency of the two different materials. Alcohols with two carbons (ie: ethanol, good stuff when derived from hops or grapes) are completely misible with water. That is, you can dissolve as much ethanol as you want in as much or as little water as you want. Acetone has limited and minor solubility in water and will behave much differently when used to thin water based paints. When used to thin latex paints, I expect that it will primarily mix with the solvent-paint fraction rather than the water fraction.
Water based paints are not water solutions of paint compounds. They are emulsions where two distinct phases exist. Droplets of paint in solvent are suspended in water by the use of emulsifying agents (sort of detergents). There is a world of difference between dilutants that mix primarily with the paint/solvent droplets and the ones that also mix with the water carrier.
Unfortunately I don't know the implications of this difference when diluting latex paints for spraying because I dilute with water and achieve uniformly good success (if I filter the diluted paint prior to spraying).
Alcohols with two carbons (ie: ethanol, good stuff when derived from hops or grapes) are completely misible with water. That is, you can dissolve as much ethanol as you want in as much or as little water as you want. Acetone has limited and minor solubility in water and will behave much differently when used to thin water based paints.
Hmmm... the ancient organic chemistry book I have at work says that acetone is 100% misible with water and that MEK is about 30% misible with water. Come to think of it... I've got another book at work that also mentions Acetone's misibility with water in the context of expressing caution about using a lot of Acetone in nitro lacquers because it's misibility with water can lead to blushing problems. I think that's in my Sherwin Williams book. I'll have to look on Monday.
In any case, I recognize that if I were to try reducing latex with Acetone that it would more than likely not behave the same as it would if I were reducing it with either Ethanol or even water. Not only does each have different solvency relative to whatever resins are in the Latex, but each also has it's own surface tension that very much plays a role in how liquids behave when they are sprayed. If you go back to where I first mentioned Acetone in this thread, I was simply thinking out loud about the possibility that Acetone might work similarly or perhaps even the same as the aforementioned Alcohol. It may very well not. But, the only way to know for certain is to try it. I'd never heard of using alcohol to reduce latex before either. I plan on trying both. Heck, my employer is paying for the materials... why not? LOL
Regards,
Kevin
"Acetone might work similarly or perhaps even the same as the aforementioned Alcohol. It may very well not. But, the only way to know for certain is to try it."
Kevin,
I agree. That's the only way to know what will work in your application [to try it]. That's one of the neat things about these forums. People can hypothetically debate the theory, and at the the same time, people with field experience can chime in also. Ultimately an answer gets worked out assuming the thread doesn't die and you wait long enough.
Jon
Most important, take respiratory precautions with all of these organic solvents and beware explosion.
Ditto!!!
Regards,
Kevin
Thank you all. I have another question about the HVLP gun. Some how I can't adjust the size of the span pattern bigger than 3 inches. the pressure was set at 10 psi per manual book. The manual book dosen't say how to adjust the pattern, I guest that one must know how to use before buying:-). Any how, the gun has two control knobs, one for pressure and one for the fluid. which one should I play first. Thank you. vn
What brand and type is your HVLP? Is it a conversion gun or a turbine driven unit? I could probably help you if it's a conversion gun. But, I've never used a turbine HVLP and don't plan to anytime soon unless someone happens to bring one by for me to play with.
Regards,
Kevin
Hi,
Tell you all the true, I just bought the HLVP paint spayer from Harborfreight to practice. It comes with 2 quarts tank and 55 inches hose extend to the gun. 10 psi min and 40 psi max but the air cap says 10 psi max, therefore I set the compressor 40 psi and regulated at the pot for 10 psi. At the gun it has 2 knobs, one for air adjust and one for fluid. After read all of yours posts again, I think I didn't thin the paint enough. I guest I have to try many time more with different percentage thinning but the hassle is to clean the gun. Has anyone have any good ideas how to clean the gun fast. Thank you.vn
It sounds like you've got a single regulator set up. They are harder to fine tune than a double regulator set up - which has two seperate regulators on the pressure tank lid. The advantage of the second regulator is that you don't have to raise and lower the air pressure at the compressor to adjust the volumn of air coming out of the gun... I would suggest buying an in-line air control (aka "cheater valve") and install it between the spray gun and the airhose that is currently connected to the gun. Cheater valves are very cheap and are definitely handy because they let you adjust the air on the fly instead of having to keep walking over to the compressor's regulator to adjust the air pressure.
That said... the 10psi max on your gun is a legal requirement that the EPA places primarily on automotive refinish operations such as your neighborhood auto body shop. You should be able to exceed 10psi if you wish to and you may well prefer the way the gun sprays at a slightly higher tip psi. I know I do with my guns. I like to run at around 20 psi for most things.
The air control on your spray gun is where you should be able to adjust the fan width. Different aircap/needle valve/fluid tip combinations will have different maximum spray width capacities. With HarborFreight I would assume that, because of the limited variety of replacement parts, your gun is probably set up to be pretty versatile in terms of fan width.
The easiest way to clean a pressure pot/spray gun set up is to turn the air off on the second regulator. That allows you to shoot a solid stream of fluid from the gun tip into whatever container you choose without having to deal with spray mist all over the place. Then you just crank the pot pressure a bit, open up the needle valve (fluid) setting on the gun and let 'er rip. Unfortunately this isn't possible with a single regulator set up unless you've installed an in-line cheater valve or have a manual valve installed at the pressure tank. Lacking either of those, you are unfortunately stuck with having to deal with the spray mist.
After spraying anything water-based you are going to want to prevent rust formations in your pressure tank and spray gun parts by flushing with denatured alcohol after you've flushed the gun and fluid line with water. The alcohol will get the water out and save you from having to replace parts all the time due to rust.
Regards,
Kevin
Hi,
I think I have a two stages compressor from Campbell Hausfeld(if I understand correctly). The compressor cranks up to 125 psi , on/off between 95 to 125 psi then you can regulate to what ever you want up to its max limitted. So it said, I regulate to 40 psi at the compressor output and at the pot I regulate to 10 psi. Yesterday, I talked to the technical guys from Harbor freight , according to him I can set max to 40 pst at the pot which that all it can handle then the gun will regulate itself to 10 psi at the output. It this is true,then I was missunderstood at the begining that I can only set 10 psi max at the pot. Boy!!! it's along way to learn. Thank you.vn.
A bigger needle will help. Check withthe manufacturer or a dealer for your gun. They'll have recommendations for latex.
"In addition, you might want to consider using denatured alcohol instead of water, as the thinner. It will have just about the same effect on the spray-consistency, but it will speed the drying time of the finished coating."
":::makes mental note:::
That's a new one to me. I'll have to try that. I wonder if Acetone would work too. It is essentially a synthetic alcohol."
Vin,
I also have had excellent results thinning latex with denatured alcohol for spraying (in an HVLP gun) I think I went about 50%. I've never tried acetone, but my gut instinct is that if you use it, you might have to thin the paint excessively since it has an extreeeemly fast evaporation rate (it may evaporate out before the paint gets to the surface). Why experiment when alk' works for sure?
Jon
Edited 6/23/2003 6:52:37 PM ET by WorkshopJon
Good point about Acetone flashing really fast. I was more wondering about compatibility than anything. If Acetone would work then MEK would work since Acetone is basically refined MEK. If MEK would work than other Ketones should work too. And once you get into the whole Ketone family... there are some really slow Ketones like MIBK, which is quite a bit slower evaporating than DN alcohol. Not that any of those would work better or even as well as alcohol. But... ya never know until ya try. First things first, though. I'm gonna try it with just DN alcohol and go from there.
Regards,
Kevin
Spraying latex
I want to spray latex paint using an HVLP sprayer. What size tip would someone recommend in order for me to achive this.
I have only sprayer lacquer in the past. Thanks for your help
Manufacturer's recommendations
I'd follow the manufacturer's recommendations, both in terms of the tip size and thinning to the appropriate viscosity.
Latex is thicker than what your sprayer is designed for so you'll want to open up the material feed as much as possible and the pressure will probbly have to be turned up higher than the manual states and this is with thinned paint. You'll get a strange texture but it will be better than brushing or rolling on a normal day.
I'd suggest using a 100% acrylic paint since it's one of the few water based paints that allows easy sanding inbetween coats. The final coat can then be a clear acrylic and the surface will look very smooth.
I honestly will be surprised if you get your sprayer to work with latex since it probably has a smallish needle in the 1.4 mm size. Harbor freight probably has a cup sprayer with a larger than normal needle nearly double the size of your sprayer intended for thick automotive primers that will work. In a pinch when my airless was clear across town and I had a door to paint I've used a cup gun with a 2.3mm needle. The material has a difficult time making it to the tip so I pre-strained the paint and removed the gun's filter, then thinned as much as needed to actually spray. Don't mess with anything other than thinning it with water or floetrol and don't have great expectations.
Another option is waiting for a rainy day and simply hand painting the object with 100% acrylic water-based paint. The high humidity makes the paint dry very slowly and if it's applied evenly it will flow out and look as smooth as a sprayed finish. If you go this route don't practice on your item, but get used to how much paint you need to flow out correctly but not drip. Every job I'm on I'll grab a brush and paint as much trim as possible on rainy days because it's so easy to get perfect results on hard to spray areas. I just wish it rained more often here!
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