1st HCL boil blue colour. 2nd HCL boil reddish/rust colour

[AUH-R]

Started to process my pins yesterday 50g in 600ml HCL. All went really well and I was done in about 3-3.5 hrs. My first batch today I thought I would do an experiment to see if I could save acid. I did 50g fresh pins in the solution I used yesterday and boiled again for 3hrs. Most of the pins stayed intact but there was a little reaction, as I can now see a lot of the kovar reddish/rust coloured small washer type bottoms of the pins have come loose. Obviously, I cannot save on acids but I'm glad I checked myself.

A couple of questions if I may:
1. The spent dark blue HCL I reused is a dark reddish/rust colour now, what reaction has taken place?
2. Can the spent solution from a normal run be used as Stannous Chloride?

Regards,

 

[goldsilverpro]

Stannous (means tin) chloride is made by dissolving TIN metal, such as 95% TIN solder, in HCl.

 

[Anonymous]

I may be missing something, but isn't 600 ml HCL to 50g of pins too much?

Kevin

 

[AUH-R]

Stannous (means tin) chloride is made by dissolving TIN metal, such as 95% TIN solder, in HCl.

Thanks, I was not sure what percentage of the saturated solution contained Tin and Lead after the leech.

I may be missing something, but isn't 600 ml HCL to 50g of pins too much?

Kevin

Hi Keven, I was just following the guidance provided by Samuel who advised 12ml per 1gram of pins.

Regards,

 

[Anonymous]

Ok then. Thanks for that info.

If you are really concerned with saving on acids and you're stripping gold plated pins, then why not use the sulfuric cell? It'll save you much money because the acid can be reused over and over again to strip your pins. A sulfuric cell is easy to setup and it'll save you money in the long run. I thought it might be hard to use, but I'm running one without any issues at all, from the first time I set it up. Believe me, if you're stripping gold plated pins, you want to use a sulfuric cell.

Kevin

 

[AUH-R]

Thanks Kevin. I started reading Hoke to death as recommended and in her day cells where new technology, so she did not really go into processes. However, the more I read the forums I realise how certain procedures are fully understood by the community and are more modern then the ones in Hoke's day. At this stage, I'm just going to take it slow get used to working with acids, recognising colour changes etc... Once I have done a few basic refines using Hoke's methods I will definitely look into the cell method, as saving money on a process is a no brainer.

Best wishes,