Concerns for the environment are changing how we think about paints. We want a product to perform well, to be non-toxic, to clean up easily, to be odor free and to be convenient, easy to use and cost effective. These are a lot of factors to consider and no two types of paint will be the same. Latex paint has been the go-to paint for decades, but the much older style of milk paint is now making a comeback.
Modern latex paint often isn't latex at all. According to Donald Groce in an article with Latex Allergy News, the resin, which used to be latex when latex paint first came out, may be acrylic or another substance. This means that people sensitive to latex can use this paint without fear of an allergic response. Latex paints are nontoxic only in the broadest sense of the word. If you ingest the paint, you should seek medical treatment immediately. Latex paints are considered safe to handle and they dry to a nontoxic surface and clean up with water.
Modern milk paint contains milk protein and can spoil and smell. According to MilkPaint.com, traditional milk paint was made from mixing milk, lime and earth pigments. There are variations (recipes) for milk paint with many different ingredients, but the basics of milk paint remain these three ingredients. Because milk paint does contain milk, people with contact sensitivity to milk may not be able to use some milk paints without risking an allergic response. Milk paint is considered nontoxic and even safer to handle than latex. It also cleans up with water.
Latex tends to be low odor or odor free, depending on which brand is selected and what level of volatile organic compounds (VOCs) the paint is rated for. According to Earth Easy, it is important to consider that while a paint base may be low or no VOC, the pigments added to the base for color may have VOCs in them that raise the level of the mixed paint. It is also important to remember that odor sensitivity varies from person to person. You should still use latex paint in ventilated rooms.
Milk paint begins to smell as it turns bad. MilkPaint.com notes that milk paint is often found in a powdered form in order to maintain a shelf life. Mixed milk paint is on the clock as the organic milk components go bad just like milk will go bad. Use the sniff test and never paint stinky milk paint on anything as the stink will not go away when the paint dries.
Latex paint is more convenient. This paint is readily available at any paint or home improvement store. It can be mixed into almost any color, and the paint, sealed in the can, will remain usable for a long period of time. Other considerations should include how much preparation to the wall surface is necessary for a good paint outcome. With latex paint, if painting over latex paint, the paint can often be applied directly over the old paint. Many latex paints can be painted directly over oil-based paints as well, although some manufacturers recommend priming for optimum results.
Milk paint is less convenient. Frequently, the paint is sold as a powder that requires mixing in order to use. MilkPaint.com notes that milk paint sold as a liquid may have synthetic paint extenders, which means it looks like milk paint but it isn't traditional milk paint. The short usable life of the paint, mixed, can be extended slightly by refrigerating the paint. Even so, a mixed milk paint is only good for a few days. These factors make milk paint less convenient. In addition, milk paint needs to be applied over a porous surface, which means that many surfaces or old paint coverings may require a bonding agent to be applied before applying the milk paint.
Because milk paint needs to be mixed it is somewhat less easy to use than latex. Milk paint is also difficult to remove, and if painted on furniture it may require additional sealant to protect the surface finish. Milk paint may also be more expensive to purchase, although increasing interest in this paint may soon make the cost of this paint competitive with latex. Milk paint does produce a look that is hard to achieve with any other paint type. Latex paint can be subject to bubbling or pulling away from the surface it is painted on, and it requires special handling for disposal purposes.