Does linseed oil strengthen wood fibers?

We have seen no evidence to support this claim. In fact, linseed oil is just a filler and provides very little - if any - waterproofing benefit. We also know that linseed oil is "mildew food", as it is susceptible to mildew growth; particularly in warm and humid climates. Extra mildewcide is required in products which contain linseed oil, and this is not usually provided.

Does pressure-treated lumber need waterproofing?

Yes. Pressure-treated wood is pretreated with chemicals to prevent insect damage and rot. It is not waterproofed. The chemical treatment actually causes the lumber to dry out quicker and absorb more water than untreated lumber. When wood absorbs water, it swells. As the wood dries, it shrinks. These cycles cause wood to crack, warp and split - this is typically what is meant by "water damage." Thompson's® WaterSeal® brand offers the most powerful protection against water damage, guaranteed.

Do silicone products protect best?

Silicone/siloxane-based waterproofers do not waterproof wood and do not pass widely accepted industry waterproofing tests such as ASTM D-4446.

Do fences-including cedar, pine and redwood fences-need protection?

All fences need to be protected from water damage. Even pressure-treated wood may protect a fence from insect damage while allowing water damage to occur. Fences that are properly protected will last longer and look better. Whether it's a fence, deck or outdoor furniture Thompson's® WaterSeal® Wood Protectors give you superior, long-lasting protection against water damage and its durable coating resists mildew and UV damage.