Bleeding is a discoloration of the topcoat often occurring as a red or yellow color shadowing.
BLEEDING (Staining) CAUSES
1. Soluble pigments (dyes) from the original coating are dissolved in the solvent of the repair materials and discolor the surface.
2. Bleeding/Staining can also occur when excessive peroxide from the polyester filler gets picked up by the solvent in the repair material and gets pulled to the top coat. The extra peroxide then reacts with pigments and bleaches the top coat.
3. The peroxide in some body fillers reacts with the polyester resin that cures the filler and creates a light sensitive photo reactive chemical which dissolves in the solvents and travels to the topcoat/clearcoat. This photo reactive chemical reacts with UV light and discolors the top coat/clear turning it yellow-brown over the filler spots over time. Light or low pigmented colors are particularly prone to this type of staining.
4. Bitumen or tar residues if not cleaned off thoroughly.
PREVENTION Spray over the original coating preferably with an epoxy primer and only use the stated quantities of peroxide when mixing the polyester filler. Never allow the colored hardener to look streaky in the body filler when applied. Use high quality stain free body fillers and prime with an epoxy primer when using light colored or transparent two tone top coats. Make sure all contaminates are removed from the substrate before applying paint.
REPAIR If the bleeding through is severe, all paint must be sanded off this area and cover with an epoxy primer first to seal area and then apply new color and clear coat.