Friday, July 13, 2007

More rhodium input from users-

Thomas from Karen Jewelers in Tennessee called me and he described some issues about plating 950Pd.

I then spoke to Mark Mann (The official tech guy for PAI) and he mentioned good results with lower voltages, warm rhodium solution and extra care in the electro-cleaning stage. He may have worked out the oddities of rhodium plating 950palladium. This post has an important caveat-All 950palladium is not the same alloy. Only Outcast from PMWest was tested by Red Sky Plating successfully. I made no attempt to test TruPd or any other alloy. There are unknown variables here. The real answer as to why palladium is tricky to rhodium plate is not yet clear.
Thomas's note to Mark Mann used by permission-

"Dear Mark,
I surely appreciate your call to me today; real conversation beats email in every way except to convey an image. The conversation may be beneficial to both of us. I did contact TechForm and that was a helpful contact.

The attached images are smaller file sizes than I could have sent but do show how we duplicated the "orange peel" or erosion of the palladium when rhodium plating is attempted. Remember, originally we duplicated the results with water and table salt as the bath.

Richard Knight did the odd formed piece of metal today and shot those photos. We had to violate every rule of jewelry photography to get the defects to show properly. Difficult was this with our "studio" of one desktop fluorescent lamp. Oh my, what a set up.

Details: This test was to duplicate the damage. Since there are many variables, the only definite conclusion is that damage did occur. Both the odd formed piece and the Hoover stock were polished to remove any traces of surface defects similar to the results shown. The odd formed piece is unknown PD950 alloy. We had one ring cast from wax by Platina and another cast from an "in-house" design by Unique Settings. Both of the castings were quite workable and nicely done. Unique did an extra fine job with theirs. The metal for the test today was taken from scrap of one of the items but we do not know which. We have no clue as to the alloys used by either Platina or Unique.

Rhodium was warm from previous use and temp was right at 100f. The Hoover stock was in the bath for 15 secs. at 2 volts. The odd piece was in the bath for 1 minute at 4 volts, a common time and voltage when we want a heavier plate on white gold.

I emphasized shadow detail a slight bit in Photoshop to allow the damage to be more clearly viewed. To the eye, the surface is cloudy and the pitting is not openly obvious. There is an obvious dull appearance due to the surface irregularities, an unacceptable condition for any item leaving our shop. You may let anyone you choose view or have copies of these photos for in-house use.""

One picture is attached of a failed attempt. Tip of the hat to Thomas at Karen's Jewelers, Oak Ridge, Tennessee for taking the time to submit the pictures of their attempts. I am very reluctant to name names of pictures of failed processes. Particularly until we have real confirmed answers to the mystery. It seems to me

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