Quote:
Originally Posted by Dpmulvan
Sodium dichromate adds corrosion protection but it won't stick to dull zinc plating. I'm not sure of the exact salt spray hours I'm sure it depends on several variables there's ton of information just google it. To answer your question
1. 10oz per gallon distilled water of sodium dichromate and 2 oz battery acid sulphuric.
2. You also make blue chromate with sodium dichromate but use nitric acid instead along with different ratios I would have to look in my notes.
This is how I do it I'm sure there's probably different ways.
3. Pull part from electrolyte bath rinse with a 5% hydrochloric acid/ distilled water solution. When a bubbles appears take out.
4. Place in sodium dichromate for 5 to seconds 10 depending on size et
5. Rinse in distilled water hang to dry.
I spent hours going through patents, reading et and wasted time and money thinking I could make a good electrolyte solution it never happened for bright zinc.
Once you look at some of the patents you'll realize it's not as easy as vinegar, salts et.
The key to zinc is the brighteners.
Caswell is the only game in town for the hobbyist, other companies will only sell with minimums that don't make sense for the home plating guy.
For $78 dollars you can buy replenishment packs and for $20 to $65 a bottle brighteners. An 8/10 plating anode off amazon and your good,
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I added brightener to my latest electrolyte batch and wanted to highlight DP's excellent comments. The brightener does make the parts more shiny and enables the yellow sodium dichromate to adhere.
As always surface prep is everything. If I forget to thoroughly acid strip the old plating, small spots where old plating remains doesn't accept the new plating or the yellow dichromate very well.
The new zinc plating adheres best to the smoothest (and shiniest) areas on the part. This can be troublesome if the part is pitted. The pitted areas accept zinc but it's near impossible to polish it. The yellow dichromate dos not adhere well to these pitted areas.
Overall, I'm still very pleased with my DIY plating setup. I can plate single parts or small batches in less time than it takes to paint them. The results may not reach a professional level, but the parts are protected and I can move on with the work. For me, that's better than halting the project to drive and hour to the nearest plating company.
Thanks again to everyone who posted!
Robert
