Paints & Coatings Resource Center

Ask the Expert Question-and-Answer Archive

by Ron Joseph

April, 2007

Thinning Latex Paint with Water -- Spraying with Airless Sprayer

Q: What ratio should I dilute water based latex paint in my airless sprayer. Everytime I use it the paint comes out thick. Shouldn't it come out as a mist? The paint is thinned with water, as far as I know. What is the ratio? Thanks for your help.

A: There is no universal thinning ratio since each latex resin has its own unique properties. For best results you should follow the instructions on the label of the can.

Having said that, let me remind you that if you over thin the paint it will loose its hiding power and you will need to apply several coats before you can adequately hide the substrate. Also, by over thinning a latex you will change its drying properties. As you are well aware, water evaporates slowly, especially in high humidity conditions. Because of the chemistry of a latex paint if you add too much water you can impair its chemical and physical properties.

If you cannot get the desirable finish from your airless sprayer it is possible that you are not using the appropriate tip orifice or that your fluid pressure is too low. By increasing the pressure you should be able to convert large paint droplets into finer ones.


Ron Joseph

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