Plating racks build up with plated metal

A. Are you sure they are nylon coated, Venkat? Nylon offers little resistance to plating chemicals. The racks should perhaps be plastisol coated?

A. In addition to Ted's comment, I would switch to stainless racks so that the stripping chemicals won't eat the exposed portion of the racks.

A. If you use stainless racks with PVC plastisol coating as suggested, then you will be able to strip in nitric acid with a controlled amount of chloride to assist in gold removal (fume extraction essential) or electrolytic in nitrate based strippers but you will also need a cyanide stripper if gold is thick.

A. Hello again, Mr. Venkat. Progress is to be applauded, so if nylon works for you, great! But plating racks have traditionally been coated with vinyl plastisol for many decades, and the reason is that vinyl is resistant to all chemicals commonly used in a plating shop whereas nylon isn't. Thousands of shops around the world have used plastisol coating in thousands of critical applications; so if you experienced "porosity", the problem was almost surely in poor execution, not in the concept.

You have already determined for yourself that you cannot successfully strip the racks with an alkaline solution, nor a cyanide solution, nor electrolytically. Geoff suggests the remaining acid and nitrate options but feels that nylon and steel are incompatible with them. Good luck, and please tell us when you find the solution. Best of luck.

A. Hello Mustak Ali

You can use plastisol coating to coat the plating rack body and exposing only the contact portion of the hook/clip. You can remove the tin coating on the hook by tin stripper either by immersion or electrolytic.

A. Hi Nigel. Oven-cured vinyl plastisol coating is used on plating jigs. A primer is applied first, then the rack is dipped in the plastisol, then it is oven baked for curing. But, like anything else, a plating rack supplier will have acquired the experience to do it right whereas another vendor may struggle.

Regards,

A. Hi again. There are "air-dry plastisol" compounds that you can probably Google and probably apply yourself for some temporary improvement, but rack maintenance -- including periodic stripping and replacing of plastisol coatings by a professional plating rack supplier -- is part of the expense of plating operations, sorry to say :-(

In the USA there is Tilton Rack & Basket, and Associated Rack Corp. (with a number of affiliates), and possibly others ... but sorry I don't know the suppliers in your area.

Regards,

A. Hi. I don't know what the primer is. It looked sort of halfway between paint and adhesive to me ... but I am pretty confident that the plastisol supplier will tell you. I am not completely confident that you will be able to buy the highest quality plastisol as it might be that they will sell it only to licensed applicators (I know that some suppliers of other products do that to maintain their quality standards) -- but I don't know, I'm just anticipating a possible problem.

My understanding of stripping is that you attempt to mechanically remove what you can with knives and pliers, then you burn the rest off in an oven to "ash" it. But my understanding of plastisol coating is second-hand and superficial -- don't put too much stock in it :-)

The "air-dry" stuff I was speaking of is, I believe, primarily a touch-up repair rather than a replacement for oven-cured plastisol. Tolber is not a supporting advertiser of finishing.com, and we do not recommend or dis-recommend any suppliers -- I just include this as an example.

Regards,