Average Time Mylars Have To Sit In Nitric/Peroxide?

Hello members,

I'm doing my first (1 lb) batch of keyboard mylars and I'm needing some info.

I have mixed a 50/50 of Nitric Acid and Peroxide. I am using 200 ml of Nitric and 200 ml of Peroxide. When I place the mylars in the acid, some of the mylars turn from a silver/white color to a grey, while some others don't seem to change colors at all... or I'm not leaving them in the solution long enough.

So, my question is "What is the average time to keep the mylars in the acid solution?" I don't want to take them out too soon, and yet, I don't want to think it takes 5 minutes per mylar when I have many more to do.

Some of the mylars did turn black and I can see that they must be stripped of the silver, while some of the black mylars don't appear to change at all. I think those are the carbon ones.

I'll also post my results and my yields from this 1 lb batch. If I get it right the first time, I'll do at least 4 more 1 lb batches to get an average yield from 1 lb of mylars. I have about 60 lbs to work with right now.

[UPDATE]
I meant to add that the the Nitric I have is 69.5%. Do I need to add more Nitric to make it 55% Nitric to 45% Peroxide?

Kevin

.../,,/

Smack said:

50/50 is fine, I use a pyrex cake pan for the shape and about the same volume of chemicals. I have the sheets cut in thirds and put them in one at a time untill they get close to not being covered by the chemicals. Then I go do something else for a few minutes like 10, 15, 20 don't really matter, they will be there when you get to them. By this time they should all be black and clean of any silver, then I pull them out one at a time and mist them with a spray bottle and distilled water into another container, let it drip well then on to the next one. I put all the stripped sheets that I think may still have silver on, in with all the circuit boards bound for the refiner, just in case I missed any silver. Don't stop at one pound, you should be able to do them all at 4 lbs., when your done take some silver that you've already refined once and dropped with copper and put into the solution to make sure all the nitric is spent, or you could save it until you have more mylars ready to do, up to you. Either way, when the reaction stops your ready to add your copper to cement out the silver. If you don't use up all the nitric, when you add copper you will have a vigorous reaction. Nitric ain't cheap so try to use as much up on new scrap (like your mylars) as possible.

Can some one merge this with http://goldrefiningforum.com/phpBB3/viewtopic.php?f=58&t=12285&hilit=mylars

If my quick math is right you should be able to get over 100g of silver with that amount of nitric.

Click to expand...

Thanks for the reply Smack!

I have some pictures I'm going to post, but there are also some time-frames I'm noticing about some of the mylars.

No# 1. Some of the mylars have been in the solution for more than 30 minutes and they're just now turning dark grey, to a brownish color then to a black.

No# 2. Some of the mylarss that are silver in color never changed colors at all, even after 30+ minutes soaking in the acid. I'm starting to believe that some of the mylars will take at least an hour or even longer to strip the silver off of it.

No# 3. Some of the mylars change colors almost instantly when they're put in the acid, turning them black.

No# 4. My rinse tray has a darker grey/brownish color after rinsing the mylars. I'm thinking my rinse is rinsing some silver in the rinse tray.

No# 5. What do I do with the rinse tray? I'm sure I can process that too, but the video I saw from Samuel-a doesn't explain what to do with it.

I'm making progress, but it's starting to get dark now and the sun is down. Can the solution stay outside overnight? I have a drawer that I can place the solution in and keep it covered.

Also, the video slideshow I saw inspired me to start my processing, but it don't mention anything about using copper to drop the silver, nor, how much Nitric/Peroxide to use per pound. Also, it doesn't explain what to do with the rinse tray.

One more thing... I want to see the yield from this first batch of mylars, so, what do I do to get the most out of the Nitric without having to waste any of it by adding Hydrochloric Acid to it? In other words, how can I get the silver out and still use the same batch of Nitric/Peroxide?

Once I get this batch completed and understand the time it takes to complete the whole process, I can perfect the method and get better yields, not unless what I recover is what it actually is to recover.


Kevin

...,,//

testerman

I'm assuming you used tap water to rinse the mylars, the rinse tray get discolored due to chlorides in the water.
The reason i suggested to use tap water and not distilled is simply the price difference, nothing else.

200 ml of 69% nitric will easily dissolve up to 150g of silver when cold (even more when hot).
The problem is that each mylar removed from the main nitric solution, some of it is lost in favor of the rinse tray.

Since the Silver on the mylars is very pure, i strongly stand against copper cementation.
Silver chloride methode is not favored by many, mainly becouse the wash cycles, but in this case the silver chloride desn't need much wasing at all.
It is up to you to choose which methode to proceed though...

Any case, you should read up some more here on the forum about the two procedures.

------

When you put the mylar in solution, try to see a change. The moment you see some change that means that the silver is off. That usually doesn't take any more then few seconds).
As you saw for yourself, there are quite a few colors left after the dissolution (black, gray, transparent etc'...). Try to compare the colors with an area that not yet been in the bath... that's about it.

Below are some pictures I took yesterday and one today to show what the rinse dish looked like when I was finish for the day. But, when I opened up the drawer today to take out the rinse dish, it was completely clear, and not the color you'll see in the last photo. I remember reading it on the slideshow that I need to let it settle overnight and it'll clear up.











I'm convinced some silver is in the rinse batch. I'll put both the nitric and the rinse solution together once I finish the rest of the mylars that are still soaking (about 30 minutes now).

Question. I have some clean copper pipe, and after everything settles by tomorrow, do I place the copper in the solution to get it to start dropping/collecting the silver? Samuel-a video says to use Hydrochloric Acid. I guess there are more ways to do this than one. Copper seems to be easier, being as though no acids are needed, yet the Hydrochloric method seem to work too. Any input appreciated.

Kevin

samuel-a said:

testerman

I'm assuming you used tap water to rinse the mylars, the rinse tray get discolored due to chlorides in the water.
The reason i suggested to use tap water and not distilled is simply the price difference, nothing else.

200 ml of 69% nitric will easily dissolve up to 150g of silver when cold (even more when hot).
The problem is that each mylar removed from the main nitric solution, some of it is lost in favor of the rinse tray.

Since the Silver on the mylars is very pure, i strongly stand against copper cementation.
Silver chloride methode is not favored by many, mainly becouse the wash cycles, but in this case the silver chloride desn't need much wasing at all.
It is up to you to choose which methode to proceed though...

Any case, you should read up some more here on the forum about the two procedures.

------

When you put the mylar in solution, try to see a change. The moment you see some change that means that the silver is off. That usually doesn't take any more then few seconds).
As you saw for yourself, there are quite a few colors left after the dissolution (black, gray, transparent etc'...). Try to compare the colors with an area that not yet been in the bath... that's about it.

Click to expand...

I often wondered if you were to use a strong H2O2(higher than 3%) and HCl if this would remove the silver as a AgCl and make recovering the silver easier without all the wasted liquid.

It seems that your silver nitrate would get too diluted and you could never fully recover the all that was still on the Mylars as silver nitrate residue. However you would be able to see the AgCl that was recovered.

Eric

When you only have PPM in your rinse water HCL will be the quickest way to recover them. The Cu will work just take longer

samuel-a said:

testerman

I'm assuming you used tap water to rinse the mylars, the rinse tray get discolored due to chlorides in the water.
The reason i suggested to use tap water and not distilled is simply the price difference, nothing else.

200 ml of 69% nitric will easily dissolve up to 150g of silver when cold (even more when hot).
The problem is that each mylar removed from the main nitric solution, some of it is lost in favor of the rinse tray.

Since the Silver on the mylars is very pure, i strongly stand against copper cementation.
Silver chloride methode is not favored by many, mainly becouse the wash cycles, but in this case the silver chloride desn't need much wasing at all.
It is up to you to choose which methode to proceed though...

Any case, you should read up some more here on the forum about the two procedures.

------

When you put the mylar in solution, try to see a change. The moment you see some change that means that the silver is off. That usually doesn't take any more then few seconds).
As you saw for yourself, there are quite a few colors left after the dissolution (black, gray, transparent etc'...). Try to compare the colors with an area that not yet been in the bath... that's about it.

Click to expand...

Sam,

Thanks for your input. I was making my post when you made yours. Once I complete the rest that I have, I'll let it settle for the night.

After that, all I do is add a few ml of Hydrochloric Acid and give it a swirl? and let it settle for a few hours or until it cements?

Kevin

Thanks for the input etack.

So, according to how much Nitric I used, I should be able to do 10 pounds of mylars, that's if 15 grams is the average amount to be recovered from 1 lb of mylars. Since I used 200 ml of Nitric (69.5) + 200 ml of Peroxide (3%), at 150 grams per that amount I used so far, I might can do 11 pounds of them.

Also, I'm thinking maybe a stronger Peroxide might be what I need because everyone of the mylars I soaked, I have personally felt the exposed silver on them, yet, some of them never changed, and some of them took at least an hour just to start to change. There is no sheeting or plastic covering them at all. For some reason I think the solution isn't strong enough, but on the other hand, some of the mylars turn from grey to completely black within seconds.

I hate to have to waste my solution after I finish the 1 lb batch, so, how can I collect what I did strip so far and still save the solution for later, or do I need to do the 10 lbs worth?

At the rate of me rinsing the mylars, I'm going to end up with a 1 gallon or more waste bucket if I need to processing 10 lbs of mylars. Or, can I let the waste gar settle overnight and siphon off the water from that?

Thanks again for all the input too. I really enjoy what I've done so far, yet, I don't want to waste anything either.

Note:... We've been having 40 mph winds here today. My stuff is secured and covered, but the wind is kicking hard and the temp is dropping like crazy right now.

Kevin

Interesting thought on your waste water... Can you let it stand in an open container in the cold?.. Would the water freeze? You could take the ice out and quick rinse and "distill" the waster water down concentrating your waste solution...

BS.
Wondering what temperature Nitric mixed with silver and water freezes...

Pantherlikher said:

Interesting thought on your waste water... Can you let it stand in an open container in the cold?.. Would the water freeze? You could take the ice out and quick rinse and "distill" the waster water down concentrating your waste solution...

BS.
Wondering what temperature Nitric mixed with silver and water freezes...

Click to expand...

I would need to take a small portion and freeze it (not in my freezer though) outside when the temp gets to freezing. But, I am not sure if Nitric/Peroxide mix would even freeze under conventional freezing.

But I like the idea you gave.

Kevin

I just came from Wikipedia and also read the MSDS sheet for Nitric Acid and cannot find any information on the word "freeze", "freezing" or "frozen" for the acid.

It's 41 degrees Fahrenheit outside right now and it's going to get to 28 degrees tonight. I'll know by the morning if it freezes, especially the rinse bowl. I'm almost convinced it won't freeze. Also, I think I need to place the gar in another container in case it does freeze, and possibly crack my gar.

[UPDATE]
It's now 39 degrees @ 5:06 PM CST.


Kevin

its a little late but, did you happen to wash the mylars before processing? certain cleaning products used to clean keyboards contain components that may inhibit the action of the acid. oils from your hands have the same effect as well as air borne pollutants such as cigarette smoke (ever walk into the house of a heavy smoker and look at the ceiling), cooking oils from frying chicken or many other sources. wash the next set in "Dawn" and dry before processing.

Geo said:

its a little late but, did you happen to wash the mylars before processing? certain cleaning products used to clean keyboards contain components that may inhibit the action of the acid. oils from your hands have the same effect as well as air borne pollutants such as cigarette smoke (ever walk into the house of a heavy smoker and look at the ceiling), cooking oils from frying chicken or many other sources. wash the next set in "Dawn" and dry before processing.

Click to expand...

You know what?.. I thought about doing that before I processed them. I bought (2) 40 lb boxes of mylars plus a gaylord of keyboards. The mylars I just processed without washing. The good thing is that I only started with just one pound of them. I have at least 50 lbs more to work with.

I'll definitely do that on my next batch because I'm too convinced that some of the mylars aren't being stripped well enough when parts of them are being stripped. I am thinking, if the Nitric is going to strip the mylars, it's going to completely strip them, not part of them. As you can see in my photos above, some of the mylars got stripped slowly, while the rest of the same mylar never changed colors at all. I can't see some parts turning completely black and the other parts staying the same color as when I first put them in the acid.

Again, Geo, thanks for that bit of info. I'm definitely going to do that on my next 1 lb batch. I figure some lukewarm water and some Dawn should clean them more to get the silver really exposed.

Kevin

wear rubber gloves during and after washing. do not handle them with your bare hands after washing. this same advice is applied to the sulfuric stripping cell material. the same effects come into play.

Geo said:

wear rubber gloves during and after washing. do not handle them with your bare hands after washing. this same advice is applied to the sulfuric stripping cell material. the same effects come into play.

Click to expand...

Done deal. I just got back from the Dollar Store. We actually had run out of Dawn. I bought the 32 oz size. I'll keep me some for myself.

Again, a very well informed suggestion. I'll never forget this.

Kevin

/..,,

Smack said:

Your planning on filtering your solution before dropping right? The one pan looks like some of the carbon may have come off, but filtering should leave your solution clean.

Click to expand...

The pan on the left is the solution, the one on the right is the rinse pan.

And speaking of filtering, I can use a regular coffee filter? And should I use distilled or tap water for the rinsing?

You know what I meant to ask?... Is it safe to bring the rinse gar inside or should I just leave it outside? It's in a drawer outside that has two big drawers, one on the top and the other on the bottom. It's now down to 37 degrees here. It's suppose to be 28 degrees by 5:30am in the morning.


Kevin

Pantherlikher said:

Interesting thought on your waste water... Can you let it stand in an open container in the cold?.. Would the water freeze? You could take the ice out and quick rinse and "distill" the waster water down concentrating your waste solution...

BS.
Wondering what temperature Nitric mixed with silver and water freezes...

Click to expand...

Here is what I found out from leaving the solution outside.

It will not freeze. So, unless I do another freeze test on it, it won't freeze. It even got down to not only 28 degrees (F) last night, it got down to 23 degrees (F), and still no freezing.

Right now I have around 1600 ml of solution/rinse, and now I need to know if I should siphon off the solution or not. I bought them in the house because it's cold outside and although the solutions have cleared up quite a bit, and I can see the silver settling on the bottom, it's still not as clear as I know it was once before.

I'll post pictures of the rinse gar and the main solution gar today.

The main solution was crystal clear, but I added the rinse to the empty gar and then the main solution to it. It's been outside since yesterday and it has cleared up, yet it's still not crystal clear. I can see through it and I can see the bottom from the top of the gar, which appears to have silver settling down on the bottom.

Maybe it settling in the house where it's warm inside, it should settle by later tonight.

Again, once I filter and let the solution settle, should I siphon off the extra rinse water or do I add the HCl to the solution?

Thanks again for all the help and advice.

Kevin

I completed the 1 lb batch already and let the solution and rinse gar settle. Now I have over 1600 ml of solution/rinse mixture.

From this point, do I siphon off the solution, or do I add the HCl?

If you notice in the photos below, the first photo is the main solution with a mixture of rinse solution on the left and the 100% rinse solution on the right.

I was thinking that I will need to use my other 1000 ml beaker and mix both solutions together to give them an even amount of mixture. But I'm still not sure if I will need to siphon off the extra solution or add the HCl to them as they are.

I also noticed that I need to filter the solution, so, my question is "Do I use a coffee filter? and since there is silver settled on the bottom already, do I use a rinse (distilled water) and put the silver in its own beaker?








My next batch I'll possibly eliminate the need to filter when I clean the mylars in some Dawn and dry them well before using the Nitric/Peroxide.

Thanks again for all the help.


Kevin