Hey guys. I thought I'd share a bit from my latest bit of research. I just found a place that does plastic chroming as well as metal, for anyone that is interested.
Also, and I know some of you will have them; I desperately need a rear overrider for my XB. One of my current one's is too corroded to be rechromed... they can do it, but they said it's most likey to come back again and the chrome wont stick too well. So guys, can you all have a good look in your sheds and see if you have a spare or a pair that you don't want! I need it to have no rust. I don't mind if it is painted... just as long as it has no rust. Thanks.
Here's a transcript of their email. They're located in SA.
About plating on plastics (POP):
The process is totally electroplating. There a no coatings applied first. The POP process was developed in conjunction with the development of plastic material known as ABS plastic (Acrylonitrile Butadiene Styrene). ABS has properties within the material which when “etched out” enable a layer of palladium to become deposited in the material surface electrolytically, thus providing the beginnings of a metallising process. ABS is a common, low cost, material type used for injection moulding of many components in the automotive, whitegoods and tapware industries.
Some other forms of plastic work sometimes but it can be hit and miss. Our industry suppliers are trying to develop a plating process which can plate any type of plastic but are still a little way off.
Where car components are concerned, in most cases the part is probably moulded from ABS and therefore likely to plate OK. The failure problems we come across are where the material is either not high grade ABS, is old, damaged, or has been plated previously. By a failure I mean the failure of the plating, or part of it, to “stick” to the part. It does not damage the actual shape of the part so it could still be used to, say, paint. Other possible ‘failures’ could include roughness in the finished item – a bit like dots of sand over the surface. This is a particular risk with old material. If the raw plastic part has been handled a lot there may also be very fine scratches etc in the surface which subsequently become more prominent once plated. Unlike metal components it is not possible to polish the surface in preparation for plating. I should also point out that even when plating brand new items the process is prone to high reject rates (up to 10%).
If the component was not actually designed to be plated there is a possibility that the manufacturer did not make allowances for the jigging of the part to a rack or wire to enable the electrical connection required in the process. This may require us to adapt a method and could result in a ‘contact’ blemish or blemishes.
We do quite a lot of plastic plating here at A Class and have a good reputation for our output of quality parts. A lot of development goes into designing the racking and methodology needed for an individual part type to plate successfully – and that’s for high volumes. When doing one offs there is therefore a bit of thinking and skill involved in ensuring we give it the best chance of success – without overdoing it and costing you, the customer, far more than you need to pay.
In terms of success “odds”, as a guesstimate, when plating one offs or old items there is probably about a 75% chance the part will plate OK - but may still have slight blemishes or roughness for the various reasons described. The odds of getting a good, relatively spot free part could be about 50-65%. (Note that large flat surfaces will have a low success rate).
Of course there are many other variables that can impact on success but I hope this helps build your understanding of the process and possible risks.