Clean Water Painting Practice

Clean Water Painting Practice

In 2024, after a year of dumping acrylic paint solids down the drain, I got serious about starting a clean water practice.

This practice aims to remove the solid paint particles from the water that I wash off acrylic paint into. These paint solids can seriously clog your plumbing and even worse, get out into the environment, where the microplastics can pollute the water supply for a very long time.

At first I thought this process would be an imposition, but it has now become second nature for me.

Here are the high-level steps in my clean water painting practice:

  • I keep a bucket partially filled with water in my studio. This is the ONLY place where I clean the paint off my hands, brushes, and any other tools.
  • After 3-4 days, this water develops a little smell, so I take that water bucket out to my garage, where I begin the paint solid removal process. I describe that process in detail below.
  • I then refill the original bucket with clean water and return that to my studio, for my next painting session.

Here are the materials needed for the paint solid removal process. I purchased all of these on Amazon (links at the bottom), but you should be able to find them at your local hardware store.

  • Hydrated Lime
  • Aluminum Sulfate
  • Gloves 
  • pH test strips
  • Coffee filters: I use the largest industrial-sized filters I can find
  • A large strainer / colander
  • A tablespoon
  • Stirring stick
  • 2 large buckets: I use 2 in addition to my studio water bucket

And here's the process for removing the paint solids from the used paint water...

I dump the dirty water from my studio bucket into one of the large buckets.

Add 1/2 tablespoon of aluminum sulfate per gallon of wastewater.

Stir the waste water well.

Add 3/4 tablespoon of hydrated lime per gallon of wastewater.

Stir the waste water in the bucket thoroughly.

"Flocculation" should start to occur now... the water seems to shimmer as the paint solids fall out of suspension. This can be a cool process to watch!

After the paint solids have mostly fallen out, test the pH of the clear water. The pH should be between 5 and 9. If it’s not:

  • If the pH is lower than 5, add more hydrated lime.
  • If the pH is higher than 9, add more aluminum sulfate.
  • Stir and wait for the second round of flocculation.
  • Then retest the pH.
  • Repeat as needed.

Once the paint solids have finished falling out of solution -- the water should look mostly clear with a mass of paint solids at the bottom -- we can filter out the solids.

Put a coffee filter in the strainer and put the strainer on top of the second large bucket, one that you’ll pour the waste water into.

Slowly pour small amounts of waste water into the second bucket, straining it through the filter and strainer, waiting for it to go down. Repeat until all water has been poured into the second bucket, carefully filtering all water through the filter.

After the last of the original paint water has been poured through the coffee filter, remove the filter and discard it.

After verifying that the remaining water looks free of paint solids, you can dump the water down the drain. (It is not fit for drinking.)

Refill the studio bucket with fresh water and return that to the studio.

This may sound like a lot of steps at first, but after a couple of times doing this, it quickly became part of my practice. I highly recommend adopting a clean water practice like this, it's good for your plumbing and it's very important for the environment.

And last, here are links to some of these products on Amazon:

 

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