At Chrometech we tell you how to pre treat the die-cast before chrome-plating
Chrome-plating the second time around after it has been pitted is rarely successful.
Reasons being: As you polish or grind the pits away you are removing the fine crystal structure of the die-cast. The more you polish or grind away the top surface, the coarser the grain structure becomes. During the electroplating process, this coarse grain structure allows more of the electroplating chemicals to penetrate the die-cast. This then will cause gassing and you could experience the bubbling effect of the chrome-plating in matters of days. Building up the craters with copper, in most cases is not successful. Not only do you have the issues with the process chemicals being trapped but the di-electrical properties between copper and zinc will accelerate the corrosion.
Our novel approach to re-chroming die-cast:
1. Stripping off the loose (peeling) electroplated surface either by electro chemical reverse current or wet &dry sanding.
2. A light bead blasting to assure that all the cavities are clean.
3. Etch prime (preferably two pack).
4. High fill (two pack.)
5. Rub back the original contours with wet & dry. (Finishing off with # 1200) Should you have the need to re-apply the High fill, you must re-coat the rubbed through die-cast surfaces with Etch primer.
1 – 5 is the labour of Love. This is the part that you do yourself or find someone that really really cares for you to do. It is not that I am lazy and we will do it if money is no object. The problem is that it is difficult to judge how long the preparation work will take and therefore I can’t quote or if I do quote it is just too expensive.
I then coat the article to be chrome-plated with a thin acrylic resin, make it conductive and subsequently chrome-plate. The acrylic resin will stop the di-electric interchange between the base copper coat and the die-cast.