Tuesday, December 16, 2008

Further Exploring Milk Paint

A couple days ago we went over a home improvement list and one of the items I mentioned as being a Greener option to latex based paints was milk paint. I received a comment from Ginger, my favorite Vegan With A Purpose, who raised an excellent point with regard to obtaining the milk for the paint. She said:

okay, i have to say it: i can definitely see how milk would be a much safer option than some nasty chemical, but considering how much land space and food it takes to sustain one cow for that milk, not to mention the consequences to her and her children, i don't think i'd call it environmentally friendly. i do like that brick wall finish though. :)

First off, thanks for the compliment on the brick (latex, fyi). Second what an interesting point with regard to the environment! It is no secret that, although I have greatly reduced my intake of anything with a face, I am still a carnivore so this was something I had not considered. In addition, I pride myself on being environmentally aware as I do my day job of painting so I was even more intrigued to dig into this question with gusto!

Ginger you raise a very interesting point with regard to milk based paints. I must admit that I have never used these paints (primarily why I suggested to try Eco Spec) so I went digging to do more research on their composition, mostly to see if milk paint is actually made from milk.

Milk paints generally come in pigmented powder form and are mixed with a liquid. The milk comes from salts of casein (the protein found in cow's milk so yes, in its truest form milk paint is actually made from the proteins of milk). The casein is the binding agent which allows the pigment be transferred to a hard surface (this is why once the powder is wet it will actually spoil, just like milk).

Before I lose everyone let me share a few key points about paint and some of the terms associated with it.

Paint is typically made up of three substances: Pigment, Liquid and Binder. When we go to a home improvement store and pull a pre-mixed can of Navajo White off the shelf we are purchasing tint (pigment), water (liquid) and latex (binder). Pigments can be derived from sources found in nature (blueberries, grapes) or created as chemical compounds in a factory. The liquid (water, oil, milk, etc) is used solely as a carrier to ensure the pigment can move across a surface and it will eventually evaporate. A binder holds the pigment and liquid together and is generally a resin of some kind (an organic substance derived from plants) which allows the pigment to attach to the liquid for application.

A fourth substance sometimes used in conjunction with paint, but not always included, is called Extender. Common uses are: for increasing length of drying (open time) or leveling (ability to spread) such as glaze, to act as a mildew resistant and, moisture repellant. When selecting extenders be sure to utilize similar properties to the selected paint -- “water and oil don’t mix”!

It is important to note the subsequent evaporation of the liquid in a paint is where the bulk of VOC will come into play. VOC stands for volatile organic compounds and are the gasses emitted into the atmosphere as a liquid dries (evaporates). This is why many painters choose to avoid alkyd (oil) paints as their solvent make up is higher. Paint might be dry to the touch in an hour or so but paint will not fully cure (dry & bond) for at least 30 days, if extenders are added it is longer and all that time gasses are being released into the space it inhabits.

So with all that said, why is milk paint a less safe alternative since it likely utilizes 100% all natural based ingredients?

As Ginger indicated it is all about the cows. To raise just four cows it is advisable to garner upwards of two acres of land. (Sadly I could not locate the exact proportion of casein to additional substances so I was not able to determine an exact number of milk required to produce one bag of paint, but for kicks let’s say it is the four). In this projection, for every bag of milk paint we would need two acres of land. These four cows would need to be fed and given water as well…and then look out for the methane gasses produced. It is estimated that upwards of twenty percent of the methane found in the atmosphere is simply from cows breathing. The more cows, the more they breathe, the more methane, the quicker that ozone layer deteriorates.

So what is a good faux finisher, painter, homeowner and environmentalist to do?

We weigh the options and determine the most environmentally sound one for our own personal benefit. Ginger is a vegan, therefore would be hard pressed to ever consider using a dairy based substance on her wall. Although not a vegan, I am concerned with the environment which leads me to use latex based paint for a few reasons.

First, more methane is produced from cows than harmful gasses are produced in the creation of latex based paints. Second, since milk paint would spoil if left to its own devices, a sealant top coat is required. That is twice the water to wash brushes and twice the product being created. Third, latex paint is readily available meaning I can purchase it from a local source if I so choose, which reduces transportation to get it to me. Finally, I am not nervous about the health risks to my respiratory system or the emission of VOC into the atmosphere due to the introduction of products like Eco Spec or other paint labeled as No VOC (be mindful that some chemicals are still emitted even with Zero VOC paints).

The bottom line is always “think globally, act locally”. Consider the overall environmental impact to the planet but make smart choices based on your own personal environment.


High Desert Diva said...

I've never used milk paint, but have always considered it a viable, environmentally friendly option.

I am now re-thinking that...thanks for this informative article!

Judi FitzPatrick said...

Thanks for sharing all of your green info, very informative.

One more type of paint to think about are those made from clay.

Not sure of the impact to the earth as I have not done any major research into them, but might be something to consider as another alternative that is natural - maybe in a future post?

Peace, Judi