How to Weather Lumber (Aging a wooden fence)

Use inexpensive ferrous sulfate to age a fence or any other wooden structure. The ferrous sulfate reacts with the tannin in wood and grays it.

I installed a new cedar fence and wanted to weather it so it would gray quickly. I bought a package of Eco Wood Treatment for $16 to make 1 gallon of solution. It advertised that not only would it gray the wood, but also protect it from decay. Because of its cost, I did some research on the web and found that this product isn't worth it. Rather, I bought a 1 lb package Ferrous Sulfate from Amazon (It is also sold in garden centers) and used it to age our fence. The ferrous sulfate reacts with the tannin in wood and grays it.

We believe the Eco Wood Treatment and similar products are way overpriced and not worth purchasing. Not only is ferrous sulfate cheaper but the claim that their products stop wood decay is true only because the iron added to gray the wood offers some decay prevention.

You can see from the photos below how a ferrous sulfate solution worked at making a fence gray. I used it on both a cedar and oak fence as shown.

Oak fence after and before ferrous sulfate treatment

Oak fence after and before ferrous sulfate treatment

Cedar post before and after ferrous sulfate treatment

Cedar post before and after ferrous sulfate treatment

Direction on Use

Mix 2 oz (3 tbl.)* of the ferrous sulfate in 1 gal of water. Then simply wet the wood you want to turn gray. In three days, your fence will be an attractive gray. People have also dissolved steel wool in vinegar to produce ferrous acetate which also will age wood in the same way ferrous sulfate does.
* I used 2oz/gal on an oak board fence and it turned the wood dry dark. You may want to test the concentration before you start your project.

Waterproofing fences with Wohlman's Classic Wood Preservative

After you have grayed your fence, you can add rot and waterproofing protection by using Rust-Oleum's Woodlife Classic wood preservative. This clear formula repels water and contains nearly double the fungicide of standard sealers or stains. It can be used as a final finish or paint primer. This is the same sealer/preservative we used as a wood conditioner before painting. Of course all wood will breakdown in sunlight.

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