cedar Stain on cast iron top

[LCHIEN]

Here's another question about cast iron tops.
I have a 6" jointer with a cast iron top. It was looking real good with Boeshield T9 and wax.
One day I left a 6" x 6" cutoff of western red cedar on the top overnight and now, where the cedar was, there's a yellow stain.

What happened, and how do i clean it?

[ragswl4]

Not a Chemical Engineer

I found this information on the web. It may or may not be the reason for your stain but I thought I would pass it along just in case. Clearly alot of it does not apply to your situation. Still looking for more.
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Redwood and cedar are forest products which contain naturally occurring chemical extractives. Woods such as redwood and cedar derive their durability and weather resistant characteristics from these chemicals. However, these chemicals can dissolve quite easily in water.

In your situation, water from several possible sources got behind the siding. This water could have been water vapor that condensed on the back of the siding after it traveled through the walls of your house. It could also have resulted from a leak in your roof. There are other possibilities as well.

The water then possibly traveled down the back of the siding and dissolved some of the extractive chemicals. When the water finally broke through a seam in the siding it ran down the siding, evaporated, and left the brown chemicals behind. This same thing can happen if water enters redwood from the surface. Water soaks into the wood, dissolves the chemicals and then is drawn back to the surface by wind action or sunlight. In any event, the result is the same.


The stains at each nail head are being caused by a chemical reaction between the extractive chemicals and the iron in the nails. Had the nails been hot dipped galvanized or stainless steel, you would not have had this problem. It may be in your best interest to replace the nails to prevent further staining. However, you can try to countersink the nails, swab the holes with a high quality water repellant, and when dry, fill the holes with an exterior wood filler.

The stains caused by the extractive chemicals and the nails can often be successfully removed. Mix one cup of trisodium phosphate, one cup of bleach and one gallon of water and wash the siding with this solution. Follow this with a solution of four ounces of oxalic acid crystals dissolved in one gallon of warm water. Be sure to use a plastic bucket to mix this solution. Wash the wood with this solution and let dry. When the solution dries, rinse with fresh water. Be careful! Oxalic acid is poisonous and can burn your skin and eyes. Wear rubber gloves and use goggles. Keep away from plants as well.

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[mpauly]

Just a few thoughts.

Did it stain the cast iron, or just the boeshield/wax layer? Have you tried cleaning with mineral spirits or WD40 and scotch brite?

Michael