The best stain for cedar siding is a semitransparent oil-free stain made from synthetic resins containing mildewcides, fungicides and UV protectants. Latex and acrylic stain bases need to be avoided.
Cedar siding tends to attract mildew, so wood stains need to repel water. Because acrylic and latex don't protect from either moisture or sunlight, a synthetic-based stain is required. At the same time, the resins found in stains that help to repel water such as linseed, vegetable or animal oils feed mold spores and must be avoided. Instead, the stains need to be treated with mildewcides and fungicides to prevent mold growth, which sunlight naturally breaks down. A good cedar stain should also contain ultraviolet protectants to prevent sun damage.
Before staining cedar siding, the homeowner needs to thoroughly clean it first with oxygen bleach. He should avoid any products that contain either chlorine bleach or sodium hypochlorite. After spraying the siding with oxygen bleach, he should allow it to soak for 15 minutes before scrubbing and rinsing it off. He can then apply the stain, which works best on new or freshly cut wood. The homeowner needs to work the stain into the wood using a natural bristle brush, avoiding lapping the stain marks. The stain should dry within eight hours, after which a second coat can be added.