You're getting ready to paint the house and you aren't sure what type of paint to buy. If the old paint is latex, another coat of the same is in order. If the old paint is oil base, then an oil primer is an absolute necessity, followed by a finish coat in oil or latex. The question is which type of paint currently exists. Here's an easy test to find out. First, scrub a small sample area with a strong solution of common household detergent. Rinse the area with plenty of fresh water and then towel dry it. Then rub a cotton ball that has been soaked in alcohol over the cleaned area. If the paint comes off it's latex, and if it doesn't it's oil base. And that's the On The House tip for today.