My HCI/Peroxide solution is turning yellow

[chrundle_the_great]

Just started a new batch of solution 600ml HCI, 200ml H2O2. Same amount I've always used and never had issues. This batch instead of turning green is yellow, like it's AR. I did skimp on H202 (about 50ml) so thought that might be the it so added about 25ml and instantly turned green. Checked back in a few hours and it was back to yellow added on other 25ml and back to green. The only difference I can think is the amount of gold pins in this batch is alot higher 18oz of pins. Any help or advice would be great!

 

[eaglekeeper]

That's way too much H2o2, do a stannous test.

 

[Lino1406]

While dilute H2O2 leaves gold as foils, concentrated H2O2 with HCl dissolves gold

 

[Yggdrasil]

Just started a new batch of solution 600ml HCI, 200ml H2O2. Same amount I've always used and never had issues. This batch instead of turning green is yellow, like it's AR. I did skimp on H202 (about 50ml) so thought that might be the it so added about 25ml and instantly turned green. Checked back in a few hours and it was back to yellow added on other 25ml and back to green. The only difference I can think is the amount of gold pins in this batch is alot higher 18oz of pins. Any help or advice would be great!

If it is supposed to be an AP solution, you use waay to much Peroxide.

You actually do not need Peroxide at all, and you can reuse it all the time.
To start a new batch, find a piece of corroded green Copper, add it to HCl and you are ready to go.
Any Copper will do but it is faster with corroded Copper.
Use an aquarium air pump to feed it with fresh Oxygen.

Did you change to a stronger Peroxide this time?
Then it is likely that you dissolved some of the Gold.
It will cement back to the Copper and other metals in the traces and the board though.

 

[orvi]

I do not know why would you add peroxide and face the possibility of dissolution of gold. Take some copper wire, place it into the beaker, pour HCL and strong peroxide, let it react and sit overnight, so in the morning copper is still left in the jar. Take this solution and use it as starter for the AP. If all copper dissolve, add another portion of copper and wait another night to react fully and spent all of the peroxide.

No possibility of dissolvnig gold.

 

[chrundle_the_great]

If it is supposed to be an AP solution, you use waay to much Peroxide.

You actually do not need Peroxide at all, and you can reuse it all the time.
To start a new batch, find a piece of corroded green Copper, add it to HCl and you are ready to go.
Any Copper will do but it is faster with corroded Copper.
Use an aquarium air pump to feed it with fresh Oxygen.

Did you change to a stronger Peroxide this time?
Then it is likely that you dissolved some of the Gold.
It will cement back to the Copper and other metals in the traces and the board though.

No, used the same peroxide as I always have. The tin I bought to make stannous I think was something else. I've made multiple batches and the tin never dissolves, just sits there.

 

[Yggdrasil]

No, used the same peroxide as I always have. The tin I bought to make stannous I think was something else. I've made multiple batches and the tin never dissolves, just sits there.

Ok what is the strength of your HCl?

 

[chrundle_the_great]

Ok what is the strength of your HCl?

Not sure at the moment, it's the HCI you can buy at the store

 

[chrundle_the_great]

Not sure at the moment, i think it's 20%. What would cause this to happen? Out of five batches I've done this has never happened

 

[Yggdrasil]

Not sure at the moment, it's the HCI you can buy at the store

20% should be sufficient for Stannous.
Where did you find your Tin?

 

[Yggdrasil]

I will delete your other unreplied posts regarding Stannous, as I regard it as double posting and that is against forum rules.