Host Scott Brown
December 3rd 2005
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Members in attendance:
The meeting was held at Scott Brown's house.
Scott Brown gave us a demonstration of anodizing at home.
Scott is using a kit he purchased from Ron Newman. Ron also has a book that is an excellent guide for the home shop user. Ron's material is available at www.focuser.com/atm/anodize/anodize.html. The kit from Ron supplies the chemicals and color dies. The containers, power supply, etc were gathered by Scott.
Webmaster note: Another source for plating and anodizing information and supplies is www.caswellplating.com -Beevo
Scott has clear plastic storage tubs to use for tanks. He uses 2 of them for each bath to provide double containment for possible spills. Scott stores his chemicals in plastic pails with snap close tops. Again he uses 2 for each chemical for double containment. Scott uses a heavy duty automotive type battery charger as his power source. He uses a Coleman propane stove as the heat source for the baths. He recommends you consider an electric cook top if possible.
Scott got a supply of auto battery acid at an auto parts store for the acid bath.
Scott uses 12 gauge wire to attach parts to the anode side of the tank. This wire is available from Radio Shack. A key tip for good finish is to have a tight connection between the wire and the part to be anodized.
The deoxidant / desmut bath is a lye solution. Scott used 1 can of red double lie in 3 gallons of water to make this bath. This bath is used to clean parts, including stripping off old anodizing as needed.
Old toothbrushes work very well to insure good cleaning in the lye bath. Brushing the part will help dislodge surface contaminants. A tip about cleaning the part. Dark spots on the aluminum part are from the 5% copper in the aluminum base material. These dark spots easily brush off The polishing of the part before starting anodizing is critical.
The surface condition at the start of the anodizing cycle is what you will have at the end. The process will put a surface finish on the part you start with. Tool marks, scratches, rough finish, etc will still be there when you are done. If you want a super smooth part, do the surface prep like polishing, etc first.
Remember different grades of aluminum will react differently to the process. 6000 series and higher work best, 2000 series tend to pit easily during if not watched during the process.
Scott recommends mixing all chemicals with distilled water. Scott tried ordinary tap water and it will work. You just don't know what extra stuff is in it that may reduce the life of the chemicals, or react in some different way.
Scott uses a small drill to cut a hole in an appropriate location on the part to attach the aluminum wire. This hole needs to be a tight fit to insure even finish on the part.
Because of the timing in a demo environment some of these steps had been executed out of the normal sequence. We needed to get a batch cooking and Scott used the striping and cleaning steps as filler.
Stripping can be done with a lye bath and alternating between the deox/desmut tank.When the old finish is stripped you may begin the refinishing process to suit your needs. This could be bead blasting or polishing or any number of surface preps.
Here is what occurred during the demo:
The first step in the process (after finishing and cleaning the part) is the de-oxidize / de-smut bath. 2-3 minutes will normally clean a raw aluminum part. Stripping old anodizing will take longer. Stripping can be done with a lye bath and alternating between the deox/desmut tank. When the old finish is stripped you may begin the refinishing process to suit your needs. This could be bead blasting or polishing or any number of surface preps.
Step 2 is a rinse in distilled water.
Step 3 dip the part in the hot cleaning solution. The recommended temp for this bath is 140 degrees. This is a specialty 740 cleaner from the kit. Using this chemical at temperatures above 140 degrees will shorten the chemical useful life.
Step 4 is rinse in distilled water.
Step 5 mount the parts to the anode bar. Be careful to keep the part surface clean. touching the surface now will cause flaws in the final finish.
Step 6 immerse the parts in the acid bath. This bath has the cathode in it, and the battery charger is connected to the bars. The power requirement could be as high as 12 amps per square foot of surface area being anodized. The acid vat should be 70 to 80 degrees. The acid bath builds the andonic layer on the part surface that is required to hold the color. This layer is like a honeycomb structure on the part surface, and is about .001" thick. Part of the that layer is being built from the part during this process. We are growing a aluminum oxide layer on the outside of the part. This oxide must be converted, if you will from an existing component. Which is of course our anode more commonly referred to as the part we wish to anodize.
Step 7 is rinse in distilled water.
Step 8 immerse the part in the color bath. This bath temperature is not critical and should be 140 degrees. Ron Newman has 140 is optimal but plus or minus a few degrees won't greatly effect the part. The part will be in this bath 5 to 15 minutes.
In the next anodizing demo we will cover more of the craft behind those fancy finishes on parts for paintball guns and such. We will cover masking, two color finishes and fades. Process planning and experimentation is where a "Real Anodizer" can paid or go broke.
Step 9 immerse the part in the NiAcetate sealer bath. This is the bath that closes the honeycomb cells trapping the color on the part surface. This bath is 180 degrees, again plus or minus won't hurt us here. The part will be in this bath for 20 minutes.
Step 10 is air drying the part.
Now you have a beautiful part.
A BBQ was held after the meeting....
Scott's friend, Lance Greathouse, had some show & tell.....
This guy scares me.......