RoHS Compliance

What sort of parts?

I doubt that answer has any bearing on a correct answer from CR4 members. Items that are in compliance with 'Reduction of Hazardous Substances' are listed with some agency as assemblies or components, and while altering your item may bring it into compliance with the content rule, it will not have been evaluated as RoHS compliant assembly, and will (probably) not be acceptable.

Not completely certain of this, but this is the gist of my understanding of the rules.

RoHS basically ban lead, cadmium, mercury, hexavalent chromium (Cr VI), and certain polybrominated phenyl compounds (mostly flame retardants) from a series of consumer products. As you can see, they are materials. It's not a safety regulation that you can get your product compliant with just by some addition or some slight modification.

An example can shed more light: An appliance or an electronic device in which tin-lead solder was used is not compliant, and there's no way of making it compliant without replacing the circuitry (perhaps alchemy could do it).

Are you asking if the elements/compounds/etc. in the material of your part can be chemically converted to other elements/compounds/etc. that are RoHS compliant?

That sounds like alchemy. Don't think that'll work.

However, if you're talking about redesigning your parts (physically/mechanically/chemically) to substitute RoHS compliant substances for non-RoHS. you may be able to.

Just depends upon your design. You will need to get your designers/materials personnel/etc. together to figure out a successful solution.

There is no way to do this. It depends on the material making up the components of a device. I work for a ups manufacture and when we decided to go ROHS to satisfy some large customers we had to check every component in every ups right down to resistors and diodes with our vendors to make sure that each individual component was ROHS. If the component was not ROHS from our vendor we had to replace it with a component that was ROHS. Once all the components making up the ups were ROHS then we could claim the ups was ROHS.