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WD-40 and Mirror Coat - a warning

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Blog entry by gko posted 08-09-2012 06:16 AM 1387 reads 0 times favorited 6 comments Add to Favorites Watch

I was testing different techniques for using Mirror Coat. I had filled the pores and had put on a skim coat of mirror coat. While it was curing I finished sharpening my chisel and had sprayed WD-40 on to prevent rust. The next day I sanded the skim coat and proceeded to put on a normal layer of Mirror Coat. I was late for a meeting so left right away. When I got home this is what I found. It took awhile to remember spraying the WD-40 onto the chisel and missing the first time. Thinking back I believe the test piece was in the direction of the the errant spray. It’s a good thing it wasn’t the 12 foot conference table I was about to finish. I’ve had this happen refinishing stuff with silicon in it and it looks just like this. According to WD-40 it contains no silicon but it sure messes Mirror Coat.   Should have wiped it down with mineral spirits.

Test sample with WD-40 mistakenly sprayed on it. Previous test piece in background without filling grain.

Btw, I’ve tried a lot of products to prevent rust on my tools, in Hawaii with it’s salty humidity it’s a huge problem. I’ve tried waxes, oils like camelia and other “rust proofing” products but WD-40 has been the best so far. I read an article recently in I think it was Fine Woodworking that did a pretty extensive test on rust proofing products and said that it was among the best products out there. There were other products that were really good but I tried to find them but couldn’t find them in our local stores.

-- Wood Menehune, Honolulu



6 comments so far

View Earlextech's profile

Earlextech

979 posts in 1349 days


#1 posted 08-09-2012 01:21 PM

Never, ever use WD40 in a wood shop. These are the results.

-- Sam Hamory - The project is never finished until its "finished"!

View NormG's profile

NormG

4185 posts in 1662 days


#2 posted 08-10-2012 01:14 AM

Wow, what a change, how can you correct this

-- Norman

View TopamaxSurvivor's profile

TopamaxSurvivor

14754 posts in 2334 days


#3 posted 08-10-2012 06:04 AM

WD-40 does not prevent rust. If you can’t find anything else, try a good gun oil like G-96.

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View gko's profile

gko

79 posts in 1903 days


#4 posted 08-10-2012 07:16 AM

To fix I sanded it flat then applied a thin coat of 1lb shellac. Shellac is one of the best finishes to seal stuff like silicon or oils. Lightly sanded and put another coat of Mirror Coat. Looking good.

I was in the other room where I sharpen my tools and sprayed the WD-40 which had the tube attached. I didn’t think it would shoot that far otherwise I can’t think of anything else that I sprayed that day. Of course it could have been my wife that shot something but I won’t go there.

I’ve tried a ton of stuff to prevent rust and it’s one of the few things that keeps my stuff from rusting. In the article it was one of the six of over twenty products they tried where rust was totally stopped. In my shop I had almost identical results with the ones they tried.

-- Wood Menehune, Honolulu

View TopamaxSurvivor's profile

TopamaxSurvivor

14754 posts in 2334 days


#5 posted 08-10-2012 07:22 AM

I wonder if they have changed the formula in recent times. It has long been common knowledge not to depend on WD-40 to keep firearms from rusting. A friend of mine, about 25 years ago, machined a steel block to test it. Overnight he could see fine rust starting. That was here in Western WA, between Seattle and Tacoma.

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View Howie's profile

Howie

2656 posts in 1581 days


#6 posted 08-10-2012 11:31 AM

I was in the other room where I sharpen my tools and sprayed the WD-40 which had the tube attached. I didn’t think it would shoot that far otherwise I can’t think of anything else that I sprayed that day.

I worked in car plants during my career in construction. Absolutely no Silicone based products anywhere near the place. Causes the paint to orange peel. Evidently,even though WD40 says no silicone it has the same effect when airborne.
I live in Florida and it’s humid most of the time. I use Outers G-96 gun spray and have never had a problem. Been using it for years. Does not affect the wood.

-- Life is good.

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