Does thinning latex paint by 10 to 20 percent radically alter its finish properties?

Question

I intend use 4 stage turbine HVLP to spray latex paint. I have not found any concrete information on what the proper viscosity of the paint should be or if it can be thinned at all. Most HVLP sprayers can not spray unthinned latex.

Answer 1

hiya richard...

water, as it relates to latex paints, is a diluent. in other words, water reduces the viscosity of latex paints without changing the film forming process (curing) or affecting the performance properties of the finish product...

other reducers, such as alcohols or alcohols blended with specific petro-chemical derivatives, will chemically react with and alter the way paint films cures - and therby possibly affecting characteristics such as adhesion, flexibility, stain resistance etc. etc. ...

thinning with water up to 20% will have no effect on the color other than, because the finish product is thinner, it may be a little more transparent leaving the previous color show through the film a little more (in other words, an additional coat or two may be required for complete opacity)...

latex paints will perform at an optimum level when applied at a specific mil thickness (depending on type of product). for example, a latex paint may be a 50% solids material meaning 50% of the paint coating is evaporative solvent. if the product is designed to perform at an optimum level of 2.0 mils dry then it must be applied at 4.0 mils wet (1 coat) or two coats applied at 2.0 mils wet to achieve a total of 2.0 mil dry film thickness.

all paint theoretically can be applied at 1600 square feet per gallon at 1 mil, so if it were to be applied at 4.0 mils thick, the theoretical spread rate would be 400 square feet per gallon.

how all this relates to how much you can thin latex paints for spraying through hvlp is this...by adding 20% water, you effectively increase the spread rate by 20% which means you now have a gallon of paint that will travel 480 square feet per gallon as opposed to 400 square feet per gallon.

while that may sound good, what you've added to your product is all evaporative solvent (water) and your solid contents remain the same. therefore, you have reduced the dry film thickness (dft) to 1.67 mils spread over 480 square feet. if your optimum performance is a 2.0 mils (dft) you can see that another coat of paint will be necessary to achieve optimum performance.

so, does it alter the finish properties? not really - just be aware that a thinner coat may not perform in the manner in which it was designed, but easily corrected by additional coats of paint.

depending on what type and brand of latex paint and hvlp sprayer you're using - generally speaking, a 4 stage turbine should be able to atomize most latex paints with minimal thinning (5% or less)...stay away from inexpensive contractor grade latex materials - these products most likely contain thixotropes designed to give paint "build" or thickness at the expense of spread rate. these products are usually so viscous that you could never spray 'em through hvlp - and you really wouldn't want to.

instead, stay with premium lines of product. typically they are thinner in viscosity already and their flow and leveling properties are so much better than inexpensive coatings. flats and low-sheened products usually require a little more thinning than the higher gloss latex coatings, but typically i spray latex enamels (satin, semi-gloss and high gloss) with little or no thinning through a 3 stage turbine.

finally, consider using flow agents, instead of thinning with water, when spraying with latex paints especially when spraying with hvlp. hvlp heats the air that atomizes the paint and sometimes results in a dry spray effect. flow agents, such as "floetrol" (manufactured by the flood company and available in paint stores) is a blend of solvent (water and glycols plus chemical soaps) to slightly retard the drying time of latex paints, thereby improving the flow and leveling of the paint film. read the label, but i think they recommend treating latex paints at a rate of up to 1 pint floetrol per gallon of paint. you'll be amazed with the results.

i hope this information is more helpful than confusing - experiment a little with some of the info listed above until you come up with a system that works best for you...good luck on your projects.

ric

Answer 2

This Site Might Help You.

RE:
Does thinning latex paint by 10 to 20 percent radically alter its finish properties?
I intend use 4 stage turbine HVLP to spray latex paint. I have not found any concrete information on what the proper viscosity of the paint should be or if it can be thinned at all. Most HVLP sprayers can not spray unthinned latex.

Answer 3

How To Thin Latex Paint

Answer 4

to this it more then 10% does alter the paint... as far as what effects it has I am not sure you would need to speak to someone at the company... I do know that if you need to thin out paint you should use flotrol or something that is meant for paint and not paint thinner...

Answer 5

OH YES.. It will change the HUE of the paint.. Be very careful..If you add one cup(for exammple) of water to a gallon of paint, make sure you do it in ALL the gallons.. This happened to me here and I had to have the whole paint job done over again because at the latter part of the painting, the painter added water.. what a mess.

Answer 6

yes. You'll not get the same finish!! Ask where you bought the paint!! They'll be happy to help you!!!