Mark-It Blue Spray Solution, 1/2 pint Mark-It Blue Spray Colorant is a non-toxic, temporary blue colorant that is designed to be added to water-soluble solutions making them highly visible when applying. When spraying in your yard and garden, it is very important that you know where you"ve sprayed so that you do not overlap or miss certain areas. Mark-It Blue Spray Colorant gives your spray a temporary blue color which allows you to easily see where where you"ve sprayed. This means less waste, more complete coverage, and safer application because you can readily see if the spray is drifting into areas you do not intend to spray. Mark-It Blue Spray Colorant is a temporary colorant. It will not permanently stain vegetation, soil or human skin and can be used with all types of equipment. The color dissipates with sunlight.