Inconsistent & Variable Copper Plating Hardness

A. I think no one can recommend anything with the very little information you gave. What chemistry are you using: sulphate, fluoborate, pyrophosphate, cyanide? And what kind of hardness additive are you adding? The only thing that I can guess is the excess of burrs comes from the same low hardness deposit (the cutting chips don't break). Give more details to try to give you an intelligent tip.

A. Given what you've said I would assume you're plating cylinders in an acid copper bath. In the sulfuric acid bath, copper plates preferentially, the additive is a controlled impurity. To successfully co-deposit the additive the current density is increased, also the concentration of the copper as copper sulphate [on eBay or Amazon]must be controlled. If the copper sulphate concentration increases, the additive cannot co-deposit, trying to overcome this by increasing the dosage of additive will leave you with organic contamination, thus brittleness. Control your copper sulphate and sulfuric acid concentrations and you should be able to consistently achieve the hardness you need.

I must agree with Hank Kudlinski here, if the sulphate and acid levels are not correct then its virtually impossible to control your hardness level.
we run a chloride free solution (and as such always use de- I water )with sulphate at 220 g/l and sulfuric 61 g/l, maintaining a hardness of 220V as this suits our higher speed engravers, lower hardness around 190-200 may be more suitable for slower or older heads.

hope this helps

A. Hi, Umma. Letter 49930 is about that topic and seems to suggest 200 Vickers. letter 38332 suggests 195 to 205 HV. Good luck.

Regards,

A. Hi, Komal. Letter 54564 and several other threads here suggest that higher sulfuric acid leads to greater, not lesser hardness. However, that letter also suggests that the heat released from adding the sulfuric acid may raise the temperature of the bath, which does cause lower hardness. Good luck.

Regards,

A. I looked in Properties of Electrodeposited Metals and Alloys [affil link to Amazon or on AbeBooks] second edition by Safranek. Its KHN is given with a 200 g weight and hardness was under 100 for a grain refined copper pyrophosphate deposit. All else was lower.

I assume that you are using a proprietary additive. What does that company have to say? If this is a home brew, I doubt if you will get your desired hardness.

"Modern Electroplating" [adv: this book on AbeBooks, eBay, Amazon] by Lowenheim lists the hardest plate as 250 vickers, kg.mm*2 from an ammonium citrate modified bath.
It also lists one as 150 - 210 °From a M & T additive, again in vickers.