# windshield washer thinned latex spraying



## kaizen (Mar 20, 2015)

I did some testing tonight so figured i'd share. I have a good air compressor and 2 homeowner type spray guns. I haven't had any success thinning it with water. Can't explain it but I've had to thin it so much its not even worth spraying. There are a lot of products out there to do this but trying to be cheap. So I saw a youtube video of someone thinning latex with automotive windshield washer fluid. I would rather spend a little more time using what I have then get a sprayer.....I don't rent stuff......and then just have it sit in my shed. so here it goes. Using interior/exterior primer that I like. very thick. The directions do not say it can be thinned. Doesn't say it can't but only directions on can is for airless sprayer. 







Figured to make this science like i'd weigh the paint and fluid. Did a 20 percent mix of fluid. It didn't discolor the white at all. I have some medium mesh paint strainers and here is just the primer. See its barely straining.







After adding the paint and fluid to another strainer it flowed nicely. it was about the consistency of buttermilk.







These are the two guns I will try. the smaller one is a detail gun. notice it has gravity feed and 3 adjustments for spray pattern, amount of product, and air. I couldn't get this to spray enough that I could make one pass and cover. I put the paint into the other gun that only has one adjustment and uses a vacuum and got better results. 














I had to shake it as there was maybe 1/4 cup left. the pattern was a little blotchy but it warrants another test with a full can. I think i'll only thin it to ten percent and see the results. Its wet out today so not sure how great of a paint job it will be. still on the fence of getting a pro airless sprayer. Here is a video to give you an idea of the speed. again took longer then normal as I had to shake it and that spitting sound is also because of the not consistent supply. I am using a husky 60 gallon compressor at 50psi. it delivers about 11.5 cfm. 

https://youtu.be/v4v_lBw3two


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## psfred (Jul 16, 2011)

I'm not sure adding methanol and detergent to paint is going to turn out well.

If the can says use an airless sprayer, that's what I would do, or get a different paint that can be thinned.

Thinning latex paints sometimes results in paint that will not polymerize properly, it turns into chalky stuff that washes off instead of sticking together.

Peter


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## kaizen (Mar 20, 2015)

psfred said:


> I'm not sure adding methanol and detergent to paint is going to turn out well.
> 
> If the can says use an airless sprayer, that's what I would do, or get a different paint that can be thinned.
> 
> ...


maybe. in theory the methanol will evaporate faster then water. not sure how much detergent is actually in it. maybe i'll do a suds test on it. I could spray oil or the like but it sucks cleaning up which is why I want to stick to latex. what would you guestimate the failure chalk time will take?
edit....just put some in a bowl and shot some water at it. zero suds. handsoap and dishsoap suds up as expected. interesting doesn't look like there is much detergent at all unless its one that doesn't suds up.


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## adson (Nov 25, 2009)

Why do you feel the need to spray paint that was made to be brushed or rolled on? 
Are you painting hundreds of boxes?


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## kaizen (Mar 20, 2015)

adson said:


> Why do you feel the need to spray paint that was made to be brushed or rolled on?
> Are you painting hundreds of boxes?


It can be sprayed with airless so there in lies the challenge. I do have enough to warrent the trial. My nucs are plywood do I make sure they have a lot of paint


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## My-smokepole (Apr 14, 2008)

Not worth dirtying a cup gun to paint them in my veiw. You would be better off with a Wooster 4" roller. If you over thin latex you will have problems.


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## psfred (Jul 16, 2011)

Latex paint is funny stuff. It's actually (or used to be, anyway) emulsified "regular paint" -- these days it's acrylic base usually, I think, dispersed in water with polymerization inhibitors in the non-aqueous part. The water dries out, leaving paint dry to the touch, but not actually polymerized until the inhibitors (usually butyl alcohol, I think) evaporate. The tiny beads of paint stick together as the polymer forms, making a porous but well adhered and continuous film.

I'm afraid the methanol will remove the polymerization inhibitor, so the paint polyermizes without first forming a film -- hence the chalk. If this is the case, it will be chalky from when the water dries and it will never get any better. Takes a while, so you may be lucky, or you may not.

I brush or roll latex, it doesn't take that long for a stack of boxes even if I'm doing ten or so. 

Peter


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## whiskers (Aug 28, 2011)

Motor oil will kill the drying ability of oil paint. So if you work the oil into a dirty brush or spray it through a (rinsed) gun you can put off cleaning. Take the nozzle off the gun and drop it into the cup with the oil. Rinse everything with thinner before you use it again. I'm pretty sure this won't work with paint that uses a catalyst.
Bill


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## Galaxie (May 13, 2015)

kaizen said:


> It can be sprayed with airless so there in lies the challenge. I do have enough to warrent the trial. My nucs are plywood do I make sure they have a lot of paint


Thanks for reporting on your experiment Kaizen!

How is the adhesion? Does the dried paint look normal, or chalky?

Yes, there are types of detergent that don't suds up. I read somewhere that suds are mainly for appearance; no suds makes the consumer think it isn't working.


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## kaizen (Mar 20, 2015)

Galaxie said:


> Thanks for reporting on your experiment Kaizen!
> 
> How is the adhesion? Does the dried paint look normal, or chalky?
> 
> Yes, there are types of detergent that don't suds up. I read somewhere that suds are mainly for appearance; no suds makes the consumer think it isn't working.


It's been dry and windy today so I will take a look tonight. I asked the question on another forum and pretty much got same answer to use water only. I certainly don't want to waste my paint but if water works I might just thin with that. Last time I used that gun like that it didn't work so should be interesting

nope no chalking. looks like a normal coat from a spray gun. not heavy like from an airless sprayer.


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