Casein: Made From Milk
How to Make Casein Glue from Milk (updated Oct.5.2017)
This recipe can be used to make a paint binder or gesso adhesive. It will give you about 7 ounces of glue.
1. Pour milk into a pan and heat the solution on low to @140°F. The low temperature is important, so don't get it too hot as to scald the milk.
2. Add the vinegar and stir slowly for a couple minutes. The milk protein will begin to coagulate into small lumps or balls. That is casein. Continue stirring for a couple more minutes until the milk liquid gets clearer. Remove the pot from the heat and allow the curds to completely settle for a few more minutes.
3. Take a spoon and remove the casein, and strain the remaining liquid through a paper filter or cheesecloth to remove the rest of the solids. The liquid can be discarded.
4. Break the large balls of casein into smaller pieces, place in a large bowl, and rinse under running water a couple times to wash off as much vinegar as possible.
5. Microwave 1/2 cup distilled water @ 20 seconds, or heat to @ 90 degrees. Add the borax powder and stir until dissolved.
6. Add the casein curds into an 8 ounce jar, and add the borax solution until it covers the casein slightly.
7. Let this sit for 8-12 hours or overnight until it forms a stiff gel. This is your casein glue that can be thinned with water for paint or gesso. Pour off any remaining liquid.
This recipe can be used to make a paint binder or gesso adhesive. It will give you about 7 ounces of glue.
- Non-fat (skim) cow's milk, 4 cups
- 1 or 2 glass jars or bowls that hold 8-12 ounces, & 1 ceramic or aluminum pan for heating the milk
- Distilled white vinegar, 1/2 cup (the ratio of vinegar to milk is 1:8)
- Cooking thermometer
- Paper coffee filters or cheesecloth, small metal strainer, paper towels, sticks for stirring
- Distilled Water, 1/2 cup
- Borax, 2 teaspoons
- Small 2 ounce jars
1. Pour milk into a pan and heat the solution on low to @140°F. The low temperature is important, so don't get it too hot as to scald the milk.
2. Add the vinegar and stir slowly for a couple minutes. The milk protein will begin to coagulate into small lumps or balls. That is casein. Continue stirring for a couple more minutes until the milk liquid gets clearer. Remove the pot from the heat and allow the curds to completely settle for a few more minutes.
3. Take a spoon and remove the casein, and strain the remaining liquid through a paper filter or cheesecloth to remove the rest of the solids. The liquid can be discarded.
4. Break the large balls of casein into smaller pieces, place in a large bowl, and rinse under running water a couple times to wash off as much vinegar as possible.
5. Microwave 1/2 cup distilled water @ 20 seconds, or heat to @ 90 degrees. Add the borax powder and stir until dissolved.
6. Add the casein curds into an 8 ounce jar, and add the borax solution until it covers the casein slightly.
7. Let this sit for 8-12 hours or overnight until it forms a stiff gel. This is your casein glue that can be thinned with water for paint or gesso. Pour off any remaining liquid.
Notes:
Use fresh (unfortified, non-homogenized) pasteurized non-fat cow's milk, if you can find it. Most commercial brands add vitamins A & E (D comes from UV light) and emulsifiers. Check with local dairies in your area or farmer's markets. What risks those additives may have on the paint or surfaces I can't honestly say, but it's not needed so it's worth the extra effort to use raw milk. I have found some raw milk at health food stores, but it was more expensive than a local dairy farm.
Borax powder (sodium borate) can usually be found in most grocery stores in the laundry section. It's made in different levels of hydration, from 20 "mule" (laundry) down to 0. The borax sold in pigment supply stores is around 5 mule. I haven't found that it makes much difference which I type I use, but the higher grade (lower mule number) may dissolve better. Borax should not be inhaled or ingested, and can irritate the eyes, so be careful with it.
Other things can be substituted for borax, like tri-sodium phosphate (TSP.) This can be found in hardware stores in the janitorial section, but is banned in some areas because of the phosphate content. It seems to work well and breaks down the curds fast, but is typically more expensive by volume than borax. Other things to use are baking soda, ammonia carbonate, or hydrated lime all diluted in the same proportions as the borax solution above. Baking soda seems to make a weaker glue, and ammonia is very acidic. Lime reportedly makes a stronger glue but a milkier paint, and can adversely affect some pigments.
Casein is an organic product, and like the milk it came from it can start to grow mold or spoil after a few days, even in refrigeration. You can add a small amount of preservative to extend its shelf-life, but it is not necessary if you only make enough for your immediate needs. Thymol (thyme oil) is a good essential oil to use as a preservative, in my experience. One drop for 8 ounces of casein gel can keep it useful for up to a year or so out of refrigeration in cool dry storage. As it gets older in this form, it won't get moldy, but it can lose adhesive properties.
I recently was able to extract casein from instant dry milk powder. I need to do more testing of paint or gesso made from this, but so far the results look encouraging. Again, make sure the product is unfortified. The benefit of this is the milk powder can be stored out of refrigeration for about 2 years, and is approximately 50% cheaper than most fresh milk at a grocery store. Here's a brand from Bob's Red Mill - LINK-.
Use fresh (unfortified, non-homogenized) pasteurized non-fat cow's milk, if you can find it. Most commercial brands add vitamins A & E (D comes from UV light) and emulsifiers. Check with local dairies in your area or farmer's markets. What risks those additives may have on the paint or surfaces I can't honestly say, but it's not needed so it's worth the extra effort to use raw milk. I have found some raw milk at health food stores, but it was more expensive than a local dairy farm.
Borax powder (sodium borate) can usually be found in most grocery stores in the laundry section. It's made in different levels of hydration, from 20 "mule" (laundry) down to 0. The borax sold in pigment supply stores is around 5 mule. I haven't found that it makes much difference which I type I use, but the higher grade (lower mule number) may dissolve better. Borax should not be inhaled or ingested, and can irritate the eyes, so be careful with it.
Other things can be substituted for borax, like tri-sodium phosphate (TSP.) This can be found in hardware stores in the janitorial section, but is banned in some areas because of the phosphate content. It seems to work well and breaks down the curds fast, but is typically more expensive by volume than borax. Other things to use are baking soda, ammonia carbonate, or hydrated lime all diluted in the same proportions as the borax solution above. Baking soda seems to make a weaker glue, and ammonia is very acidic. Lime reportedly makes a stronger glue but a milkier paint, and can adversely affect some pigments.
Casein is an organic product, and like the milk it came from it can start to grow mold or spoil after a few days, even in refrigeration. You can add a small amount of preservative to extend its shelf-life, but it is not necessary if you only make enough for your immediate needs. Thymol (thyme oil) is a good essential oil to use as a preservative, in my experience. One drop for 8 ounces of casein gel can keep it useful for up to a year or so out of refrigeration in cool dry storage. As it gets older in this form, it won't get moldy, but it can lose adhesive properties.
I recently was able to extract casein from instant dry milk powder. I need to do more testing of paint or gesso made from this, but so far the results look encouraging. Again, make sure the product is unfortified. The benefit of this is the milk powder can be stored out of refrigeration for about 2 years, and is approximately 50% cheaper than most fresh milk at a grocery store. Here's a brand from Bob's Red Mill - LINK-.