How Much Thinner Do I Need to Thin Kilz For Spraying?

If you need to apply a smoother or thinner coat of Kilz, it’s totally safe to thin the paint before using it. Thinning Kilz before use does not reduce its quality, and thinning the paint will help it dry faster and roll on smoother.

To thin Kilz for spray applications, add 1.5 pints of water or mineral spirits to the paint container. Stir the water or solvent into the primer until there is no separation. It should then be ready to go on with a paint roller or spray gun.

This article will explore the “hows” of thinning Kilz without reducing its quality.

paint thinner added to Kilz for spraying

What Can You Use to Thin Kilz?

Thinning Kilz primer is relatively easy. But before doing so, you need to determine if you’re using a latex/water-based primer or oil-based primer. Organic solvents are most suited to oil-based products, while water can thin out latex/water-based ones.

Keep in mind that not all organic solvents can effectively thin oil-based primers. Therefore, it’s safest to stick to popular, tested choices like mineral spirits or denatured alcohol.

How to Thin Kilz For Spraying: A Step-by-Step Guide

If the area you want to prime is relatively large, it would be much easier to use an airless paint sprayer (also known as an electric paint sprayer).

If you’re painting an exterior space, that’s even better—you won’t have to worry so much about where the primer lands.

Let’s look at the steps you need to follow in order to thin Kilz primers and paints.

Material List

house painter with facial protection sprays paints a home's deck

Household cleaning tools are handy here. Start by raiding your home and gathering the following items:

  • Bucket
  • Stirring rod
  • Water or mineral spirits
  • Air-fueled or airless sprayer 
  • Safety gloves
  • Respirator or face mask

Safety equipment like gloves and respirators are on the list because Kilz (and solvents like mineral spirits) emit harsh fumes and can irritate the skin.

What Type of Primer Are You Using?

Always check the instructions on the products you purchase to know what the manufacturer recommends for thinning them.

You can thin latex-based primers like the Kilz Latex Primer, Kilz Premium Primer, and Kilz Maximum Primer with water. But their oil-based products will require a harsher solvent, as water and oil don’t mix well. 

Some cans may also give you the ideal solvent-to-primer ratio for thinning.

Measure Out Water or Thinning Solvent

hand holding a spray gun to paint a wall

Generally, you need 1.5 pints of water or solvent per gallon. After measuring, mix the water or solvent and primer in a bucket; stir until smooth.

If your thinner didn’t come with a ratio guide, remove a pint of Kilz from your portion and replace it with water. 

Test with a Paint Sprayer

After mixing thoroughly, pour a portion of the thinned primer into your paint sprayer and try it out on a test surface. 

Thicker paints may need to be thinned more in order to spray well. If it has a hard time coming out of the paint sprayer, then you need to thin the product more. An even mist means it’s thinned just right.

Remember the Correct Mix Ratio for Later

If you had to make any adjustments during the last step, now is the time to take note. That way, you can avoid the hassle of trial and error next time you try to thin the primer, saving your time and sanity.

How to Apply Kilz Primer with a Sprayer

man painting a grey wall with spray gun

When you go to spray the primer on your wall or another surface, be sure to follow these steps so you can get it just right:

Prepare the Surface

This is vital, as the surface acts as the foundation for your primer. If the surface is clean, your primer and paint will look clean, too. This is true for new walls and old walls or fixer-uppers alike.

If you’re working on something like an old fence, be sure to scrape off any old coats of paint. If you’re priming a glossy surface, sand it down so you can get more excellent adhesion.

Spray the Primer as Evenly as Possible

To achieve this, choose the best sprayer. Before you start, inspect the nozzle tip, spray pressure, and filter mesh size.

The standard tip size should be about 15 to 21 thousand tips. The ideal pressure is 1800 to 3000 PSI, and the mesh size should be around 60.

Apply a Second Coat if Needed

While some walls may not need you to apply a primer coat twice, others might. Fire-damaged or heavily stained surfaces will need a second coat to prevent bleed-through, giving the surface a neater finish. 

Just ensure you don’t add too much primer, as this can actually mess up your paint job.