Potassium Dichromate for Schwerter's silver test solution

[kadriver]

I am going to buy some potassium dichromate to make Schwerter's test solution.

I have found two recipes on the forum:

1) HNO3 + K2Cr2O7 =Schwerter's Silver Test Solution = Add 20 grains of potassium dichromate to 30 mL of 35% nitric acid. Test by applying a single drop to clean silver surface.

2) Here's an alternate method for making the silver test solution:
1.Dissolve Potassium Dichromate salt in 8mL of distilled water in a glass container. Add crystals until no more salt will dissolve in the liquid.
2.Add 25mL of 70% Nitric Acid
3.Store in a small bottle.

Does anyone have any experience that could be shared with either of these recipes? Is there an advantage of one recipe over the other?

Does this test solution expire or go bad after a certain time period?

I purchased a nice 75ml glass bottle with a ground glass top cover and a glass dipping rod to store the test solution.

Thanks - kadriver

 

[metatp]

I can't remember the receipt I used (I will have to check my records), but I made about 50-70ml. I store it in a Pyrek glass bottle with a plastic lid. It has lased me a long time with little sign of going bad. I use it in a small plastic sqeeze bottle. In the squeezed bottle it only lasts about a month or two with almost daily usage.

 

[philddreamer]

Kad, I don't know the price of potassium dichromate, but I just received a shipment of 12 bottles of Schwerter's test solution for $20.00, free shipping from this outfit:

http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=160680245643

Take care!

Phil