Wood Bleach/Oxalic Acid

I mentioned in my post "Rust the New Black" that I was going to try using wood bleach to remove some rust.  What follows is my result.

The first item I decided to test wood bleach on was one of my hubcaps.  It had a combination of surface, built up and eating through rust.  My ultimate intention is to strip all the rust and paint then cover with Dover White paint. The interesting part of the hubcap is that in many ways it should be simple to remove the rust with a blaster or wire brush, however the backside has some challenges in that the lip is not easy to get to with those methods.  Yes I know that nobody will see that side but I will know its there and I want a clean part.  Also since I'm not worried about ruining the paint on the hubcap I figured this would be a great test of the wood bleach.


I called a good friend of mine who owns an awesome hardware store in Rogue River, Oregon (www.mainbuilding.com)  and he brought over a small tub of wood bleach.  Now the instructions on the container are for wood not metal.  I decided to start with a gallon of water and 2 tablespoon of wood bleach powder.  This was just enough water to cover the hubcap in the 5 gallon bucket.  I mixed the water and powder for about 30 seconds then plopped the hubcap into the bucket upside down.

So far the hardest part of this has been getting the lid off the wood bleach without scattering powder everywhere.  I went back to making dinner and then returned an hour later to check on the part.  I could see that the surface rust had diminished but the built up sections were still intact only wet.  

This was not looking well.  

I decided to increase the wood bleach, so I added 4 more tablespoons to the gallon of water.  I also decided to see if perhaps the rust was just sitting on the part and all it needed was some gentle steel wool to remove the rust.  I was pleased to see that the scrubbing was improving the rust on the surface but still required more effort on the backside. Removing my gloves I left to go watch a movie.

It was now about 4.5 hours of soaking and it looked a little better than before but honestly nothing that I could recommend at this time.  Perhaps a combination of wood bleach and wire brush is the answer but what I was really hoping for was a complete removal of rust and very little elbow grease involved.

In the morning as I was leaving for work I checked in on the hubcap and to my surprise the rust was GONE!  I was already running late so I could not take the part out of the solution and inspect or take pictures but when I lifted the cap up and out of the water it was clear that the surface of the hubcap was metal not rust.  When I got home it was about 24 hours in the bucket before I could remove it and clean it with fresh water. A bit of final scrubbing with steel wool and the result is fairly good.  I dropped another hubcap into the solution last night and again in the morning it looked remarkably clean.

Now that I know this works, I'm excited to try placing my fuel filler in and seeing what happens.  That part is about $60 and it looks real bad inside.  Even if I have to increase the ratio and or leave it over a few days anything will be better than trying to scrape and brush the part.  Stay Tuned!

UPDATE:  I have noticed that parts left in the solution will have the paint soften and start to come off.  Not a big deal since I will be repainting them, but if you have paint and want it to remain think twice about using this process.  I also increased my concentration to 10 tablespoons per gallon vs the original 6, to see what would happen.  Not a noticeable difference, except perhaps a bit quicker on the rust removal.  Will probably stay at 6 tablespoons per gallon for future parts as 24 hours seems to be my standard waiting time.  I drop parts in at the end of my day and let it work while I sleep. 

UPDATE: Fuel Filler.  The fuel filler was a mess.  I let it soak for a few days and then also used sand paper, steel wool, small wire brush and a screw driver to clean it up.  The photos are only before I used other tools to clean it up.  After all of this work, a member of the Old GMC website (Thanks Jerre) gave me a nice clean fuel filler.  I'll use his instead since it is much cleaner and has no issues.