UPDATE: Hold The Micro-Plastics, Please

This is an update on the February 2023 blog post I wrote containing helpful tips for artists who use water based paint to reduce the amount of paint contaminants being rinsed down the drain. If you haven't read that blog yet, I encourage you to do so and learn about all the tips I list there to lessen the amount of paint going into your rinse water in the first place. Since writing that original blog post, I have also begun a very satisfying process that I use about once a week to separate paint solids from my rinse water! This process is called FLOCCULATION, a very fun, science-y word which simply means to clump. So, come along with me and let's clump and remove those water-based paint solids and prevent them from gunking up our pipes, septic systems and the water table. It's easy, I promise.

Supplies

Here's what you'll need to get started. I found most of these things at my local hardware store/garden centre in one Saturday afternoon. According to my receipts, I spent about $70 CAD, but some of the things I purchased probably could have been sourced for free if I had just spent a little more time looking around my garage! Also, I suspect that these supplies will last me for a lifetime of flocculation.

• Aluminum Sulphate - often used to acidify soil in gardens for acid-loving plants like hydrangeas. You can find it in the garden supply isles.

• Hydrated Lime - used as a soil conditioner, but also for the production of mortars, plasters, cement etc. I found some in the hardware store.

• Safety goggles and a dust mask. Safety first, people. Plus, this is science. Look the part.

• 2 plastic pails - Mine are around 1 gallon. You might like one to have a lid to keep paint water covered until you're ready to process it. Mine is a repurposed gesso bucket. If you paint BIG, use large brushes, lots of acrylic gels, fibers, pastes and/or generate a lot of rinse water in your practice, you may prefer to use larger pails so that you don't have to flocculate as often. Note that one pail will be used to filter the cleaned water into, so your funnel (listed below) should sit nicely atop it. If the circumference of this pail is too large for the funnel to rest on, you will be annoyed, so be forewarned.

• A big stir stick. A free paint stick from the hardware store works well.

• Measuring spoons (don't use the kitchen ones). I picked some up from the Dollar Store to keep with my flocculation supplies.

• A big plastic funnel. I got one from the automotive section, intended for oil changes I'm guessing??

• Large coffee filters or filter paper. Again, Dollar Store.

• PH paper. This is the only thing I couldn't seem to find locally so I ordered it online. You may be able to find some in the aquarium section of your pet supply store, at the pharmacy, the garden supply centre, educational supply....probably lots of other places that don't immediately come to mind.

The Process

Filtering flocculants in my jacuzzi tub.

1. First, stop pouring your brush water down the drain. Pour it into your big collection bucket instead. Weirdly, I keep mine in the jacuzzi tub which mostly sits unused and is a handy storage space. Before you pour, run a brush around the bottom of the container to loosen any particulates that have settled. I then like to add a little clean water to the bottom and really rinse the container and my brushes as well as I can, then add that to the big bucket, too.

2. Keep collecting your brush and rinse water in the bucket until it's full or nearly full. If I'm painting full time and being fairly conservative about how much rinse water I use, I will need to flocculate about once a week. Keep a lid on your collection bucket if you choose.

3. On flocculation day (!), put on your safety gear and then measure and add 10 grams of aluminum sulfate per gallon of dirty paint water. This is about 1/2 a well-rounded Tablespoon. You can dissolve it in a bit of water first before adding but I don't because I like to live dangerously and cut corners. Stir well with your stick to dissolve the crystals and suspend all those paint solids.

4. Next, add 9 grams of powdered lime per gallon of dirty paint water. This is slightly less than 3/4 of a Tablespoon. If you are a measuring person (you know who you are) and this makes you uncomfortable, please accept this virtual hug 💛. Stir with your stick and watch the magic of flocculation unfold before your eyes.

5. When you stop stirring and the water begins to still, you will start to see a clear layer of water forming as solids clump and settle. Yay! If, after several minutes, this hasn't happened, repeat steps 1 and 2.

6. Check the PH of the clear water using the PH paper. It should be between 5 and 9 - not too basic and not too acidic. If the number is too low (basic), then add more lime. If the number is too high (acidic), then add more aluminum sulphate. I have never needed to do this but I suspect certain additives in your rinse water, like soap, could cause this. I have never had a problem and the PH is usually around 6 or 7.

7. Once flocculation has occurred, layer up two coffee filters in your funnel and place the funnel atop your 2nd bucket. Carefully pour the flocculated water onto the filters. I pour only a bit at a time to be sure that all water is getting properly filtered. If your filters are getting gunked up quickly, you could replace them with fresh ones between pours and speed up the filtering process. If your rinse water was super dirty, the water will take several hours to completely pass through the filter. Toss the dirty filters into the garbage to be sent to the landfill. If your filtered water isn't clear, pass it through a filter a second time. The clear water can now be poured down the drain!

   
   

   

   Leftover paint sludge! How satisfying! I was obviously using a lot of blue this particular week.

   I hope this blog post has inspired you to take action and make your painting practice a little more eco-friendly. Most of the information I have provided here was sourced from the Golden Artist Colors website blog, Just Paint, which has a wealth of resources for artists, including a handy print-out for this flocculation process. If you give it a try, let me know how it goes!

Bixby says 'hi'