Tannin staining
 
Cause

Some cedar woods contain colored dyes such as tannin which is water soluble, and other colored extracts which are soluble in mineral spirits. In these instances, a primer that has discolored should be spot-tested with a second coat of primer or a latex topcoat to determine which will successfully block future discoloration.
 
Solution

New red-colored woods must be sealed with an undercoater that will function as a barrier coat, preventing staining of the topcoat. This undercoater can be either a solvent or latex primer, depending on severity of available tannin dyes in the wood.

Although the latex primer contains water, the product chemistry is designed to minimize surface discoloration by tannin bleed. Extreme cases of tannin bleed may require one or two coats of alkyd primer to prevent discoloration.
 

Recommendations: