Getting Platinum crystals back into solution ?

[Dennis]

The title pretty much says it all. I have a couple of 25 ml bottles of Bostick and Sullivan standard Platinum solution number 3. Down to the last 4 or 5 ml in the bottles and they have gotten quite a lot of red crystals in them. I have added 8 drops of distilled water to each and heated them in a tray of hot tap water and shook them till I was late for dinner and left them sitting all night and in the morning no improvement at all. Does anyone know what I should do?


Thanks Dennis Purdy

[tgtaylor]

Dennis,

If what you have is platinum chloride, ptCl4*5HOH, Hawleys Chemical Dictionary says that it's red crystals "soluble in water and alcohol;" "d 2.43, mp loses 4H2O at 100C."

Call up B&S. I've found them very helpful and willing to share their knowledge.

Thomas

[Louie Powell]

You can probably add a few drops of distilled water to dissolve the crystals. But the problem will be that the final dilution will be quite different from the standard B&S product. Pt/Pd solutions are usually mixed in drop quantities, usual a 'formula' that you evolve over your experience in printing. If one of the solutions is a different concentration, the results can be quite different from what you expect. If you only have a minute amount of Pt or Pd left in the bottle, the most controlled approach might be to just dispose of it on the basis that even if you can get it back into solution, you won't have enough to recalibrate your drop formula.

And yes, I know that the notion of throwing away any Pt or Pd is mind boggling given the price that you have to pay for replacement metal solutions.

[Dennis]

I did contact Melody with the problem first. She suggested that I should add little at a time distilled water till it goes back into solution. I did that but it ended up taking more water than I expected. I called Melody again and she said a person can always send it back to Bostick and Sullivan and they will recycle it and replace it with useable stuff. Don't throw anything away if you can help it.
For now the stuff is back in solution.
Dennis

[tgtaylor]

Alternatively you could melt the crystals at 370C (WikiPedia indicates a melting point of 370C http://en.wikipedia.org/wiki/Platinum(IV)_chloride)and then add distilled water to bring it back to the same concentration as the original B&S solution. Coincidentially the high temperature of my Corning Ware Labatory warming plate which UPS brought yesterday is 360C. So if you don't melt it yourself or send it back to B&S, mail it to me instead of throwing it away. I may be able to melt it.

Thomas

[Dennis]

Strange. I got it all back into solution at 120 F but when it cooled it went back to crystal though I know it has too much water in it now. The I looked at my new unopened bottle and it has turned mucky as well.
So I am sending it all back to B&S as per Melody's instruction.
Dennis

[tgtaylor]

I thought that the crystals should disolve at a temperature approaching, but not quite, 212F. Next time that happens I recommend carefully weighing the crystal before disolving so that you can add enough distilled water to bring it to the exact concentration needed.

Interesting question and a situation I'm sure to face in the future.

Thomas

[Louie Powell]

Alternatively you could melt the crystals at 370C (WikiPedia indicates a melting point of 370C http://en.wikipedia.org/wiki/Platinum(IV)_chloride)and then add distilled water to bring it back to the same concentration as the original B&S solution.

Am I missing something? Water boils at 100 deg C, so if you heat the crystals to 370 degrees, the water will flash to steam rather than dissolve when you try to add it.

Warming the solution may aid redissolving crystals, but I don't think melting the crystals at a high temperature will help, and potentially could be dangerous.

[tgtaylor]

Folks are melting gold at home and gold has a much higher melting point, => 1000C, than the crystals above. Actually aqua regia would be a better solution for melting platinum but the crystals apparently re-dissolves in warm water.

Thomas