Anodizing a part at home

Scrap 6061 that will become the donor electrode

Showing the donor electrode in place

The part to be anodized

The process under way

After anodizing, before staining

Staining the part in Rite Dye

The part after anodizing and staining

The finished part on the engine

This process was posted on the CorvairListServe by Phil Hartig. I've cleaned up the text a bit to make it suit the Build Wiki better, but the text and pix are his.

All the red parts you see in the final engine photo were done in our shop. The prop hub was also done in house. The hub was left with natural anodized dull silver finish. With the exception of the hub, this is all for aesthetics as the parts are 6061 aluminium. The demonstration part shown is the tachometer pickup.

• Take a large glass beaker and wrap a piece of scrap 6061 round the edge. This is the donor electrode.
• We bought two one-quart cartons of of sulfuric acid from AutoZone.
• We wanted to dilute the acid, so we poured in two quarts of distilled water into the beaker and then added two quarts of acid (always add acid).
• The part was then suspended on a strip of thin 6061 and press fit against the part in a place that would not show. The other end of the strip was fitted through an old piece of plywood. Then the part was lowered into the acid.
• We used a 10 amp battery charger to power the reaction. The negative end goes on the donor electrode and the positive on the part.
• We ran our reactions for one hour, or until the amps drawn reaches the max output of the charger.
• The part is then rinsed in water and placed in a pot of 65 degree centigrade RiteDye (In this case red) and kept several minutes until we got the color we wanted.
• The part was then rinsed in water and then boiled in fresh water for 30 min.

Other observations:

• It is very important the part be very clean. We wash them in degreaser and rinse thoroughly in water.
• All the water we used is de-ionized.
• This process should be done in a well ventilated area or you will burn your lungs.

External linksfrom Phil's text

Phil's Picasa site. There aren't any notes there, which is why I put the pix and notes' sequence together, here.

Further notes about anodizing

Van of Van's Aircraft notes that an article in the Dec 1991 issue of ''The Rvator'' that addressed the issue of anodized spars and the effect on fatigue strength, specifically from the point of view of a trade-off against corrosion. The question was what does anodizing do to the service life of the spars? His conclusion was that anodizing offers more than double the corrosion resistance of priming. However, it also reduces the fatigue life by up to 50%. The normal fatigue life was computed to be 24,000 hours on regular acrobatic use so the anodized life would be 12,000 hours. That would be 80 yrs at 150 hrs/yr. These were considered conservative numbers. lf you get corrosion in a spar it lowers the service life so anodizing them is a good tradeoff.