Not very long ago most paint was simply oil or water based. In response to environmental impact concerns, paint formulas are now all water based, some acting like oil but still water based. When paint formulas change, so do the formulas for your color, and often times the new formulas are not as durable because they don’t adhere to the previous product. This is important to know because it means that the exact color and formula you used before may not be available again when you want to do some touch-ups or repairs.Paint bases are manufactured in lots and come in dye lots just like fabrics and carpets. Dye lot matching comes into play when you want to get more of the same paint due to under estimating your needs and it was mixed with a base from a different lot. This is why they are numbered and you should be sure all the paint you buy for a single project is mixed with the same lot of base and at the same time. If you come up short, it could mean that you have to custom match your paint, but even then the result may not be satisfactory. So what should you do to prevent this problem? It’s easy; when you are buying paint make sure that you don’t get too much, but buy a little extra so you have some for repairs that will match perfectly. Use the link below to figure out how much paint you should be buying for your space and then add on a bit more for insurance.