Making AgNO3 Solution

The making of AgNO3

One of the most important ingredient in the wet plate process would be the silver nitrate (AgNO3) solution itself.

Though this particular effort in turning silver to the solution has its peril,dangers, and certainly not for those without proper knowledge or at the least to have the proper lab technician present to advise.

Making this solution, for me, has its perks, one, it is cheaper than buying from the manufactured, as what it costs me was the acids, lab gears & time, and of course the silver as the materials itself. Though what was made here would not be 100% pure as there is a small percentage of other metal or material present! as it depends on the purity of the silver itself.

Though, with imperative warning I must give before considering to venture into this, do not try this at home, do not do it if you do not have the proper facility to make this. I will not be responsible for any injuries, fatalities, accidents, or incidents which could occur from this blog entry. Or even guarantee the satisfactory in the results of solution’s quality arrive from this chemical experiment. Hence, this disclaimer must be presented and you have been warned.

Ok, now on with it…

Previously I shared this information in a forum of this practice (the wet plate collodion), in which it had its shares of disagreement to whether this information should be shared commonly. I argued careful steps needs to be made, planned, and of course heed thoroughly understood of its materials, precautions, and chemical reactions based on the Material Safety Data Sheet (MSDS, or MDSS).

Though now it would have been buried so deep in the forum’s history, or possible it could have been deleted. In my personal opinion, whatever chemistries you handle, it must be made without discounting the methods done properly and safe.

The silver I had in hand was extracted from scrapping disposed electronic parts and among those commonly found. To be honest, looking at the quantity retrieved, it had taken me awhile to reach at 100 grams of silver. Thus the question of making your own silver nitrate solution was worth it, in my personal and economic opinion, not in small quantity.

On another note, I apologise for the images as it was taken in a darkened lab, as I do not want the silver nitrate to start reacting to light.

Silver scraps, 100 grams

Scrapping, had its possibility of the silver would be difficult to have it pure. As mine had the presence of copper in it, as later results of the silver nitrate had bluish green tinge/tone to it.

Plus, the process of scrapping was taxing to even reach 100 grams. My untested guess, the silver was at 93% pure based on this sample.

List of required items:

  • Silver – pure or refined scraps
  • Nitric acid (65-69%)
  • Silica gel
  • Potassium carbonate powder
  • Bowl of ice
  • Lab Pyrex / borosilicate container and flasks
  • Glass stirrer
  • Plate heater (optional copper sheet for even distribution of heat)
  • Fume cabinet
  • Gas masks, eye/face protector, nitrile gloves, welding gloves
  • Dark chamber/ container

The formula:

Ag + 2HNO3 -> AgNO3 + NO2 + H2O

Atomic weight Ag: 107.868

Molecular weight AgNO3: 169.88 (estimated weight of the silver nitrate crystals by the end of this experiment).

Weight of Ag: 100g/107.868 = 0.927

2 Moles of HNO3: 126 mL

x 0.927 = 116.8

Required nitric acid for 100 grams of silver= 116.8 mL

Nitric acid and heating plate

The steps

1. Prepare all the equipment and the safety gears in place.

2. In Pyrex or borosilicate flask, pour in the acid at the mentioned quantity (116.8 mL, to process the 100 grams silver).

Place these items into the running fume cabinet.

3. Mix half of the silver into the nitric acid gently (wear all the safety gloves, double layered nitrile gloves and top with the welding gloves. Stir slowly of the silver bits mixture with the glass rod.

4. Slowly heat the acid (with half of the silver in it), to 80′ C. It was noted at this point the nitrous oxide gas had started to fume at this point.

Silver reaction in nitric acid 

5. After 20 minutes, slowly build up the heat to 100’C; Drop in the rest of the silver into the heating flask, carefully done without splashing the acid.

6. Observe the reaction as the cloud of nitrous oxides starts to grow thicker, reduce down the temperature slightly to lower the reaction.

Nitrous oxide fumes reaction from heated nitric acid and the silver

7. With the bowl of ice pick up the flask (protect the hands with the welding gloves), place the flask into the bowl of ice to significantly reduce the boiling and slower the reaction.

Cool down the reaction with a bowl of ice

8. Replace the flask back onto to heating plate after the cool down.

Continue with the heating of the flask.

9. Continue heating the nitric acid til the nitrous oxide fumes subside. I had noted here the fume had began to decrease as the reaction turning the silver to silver nitrate began to form to completion.

Turn off the heating plate at this point and let the solution to begin its crystallisation and the H2O to evaporate.

Reaction of nitric acid to silver almost complete.

10. As the solution had evaporated and left a noticeable crystallisation, leave the flask to cool down to room temperature and also to clear out any remnants of nitrous oxides to disperse from the nitric acid reaction.

Drying and crystallising the silver nitrate in dark chamber

11.  Once the reaction had stopped, move the flask into a dark sealed chamber/box alongside with two dishes of Potassium carbonate (to reduce and rid of acid), and silica gel (to dehydrate the solution of water) separately.

12. As mentioned earlier, the solution seemed greenish blue, which probably had a small quantity of copper in the silver, further steps could be done to purify it, but I prefer to test the solution for workable wet plate process.

The silver nitrate after 3 days of crystallisation, it appeared to be damp and wet, which indicate the presence of water. Further drying time and replacements of silica gels and potassium carbonate continued for another 3 days.

13. I had left the drying and de-acidifying in the dark chamber for 3 days, there’re was still a bit of water left in the crystals, which I replaced both potassium carbonate and silica gels to do its work for another 3 days.

14. The end result was at 158.68 grams of silver nitrate crystals , in which it had a bluish green tinge to it, it could have been more purer if I redo it with hydrochloride acid and repeat the nitric acid to further purify it, but would it be worth the trouble?

The silver nitrate, with slight bluish green tinge, will this work to produce images for wet plate?

Though, based on the calculation, there was less of silver nitrate by slightly over 10 grams, which I suspect I get most of it back by properly scraping the flask every centimetre of it.

The following image was done with the same silver nitrate. Further tests would be needed on the long run.

AgNO3 test, “the window studies”, 2013. Wet plate collodion on clear glass. More notes will be conducted of the silver nitrate made from this batch.

In the end of this note, some probably would enquire whether if it was worth it to go through of danger in making the silver nitrate. In my personal opinion, why not? There is certainly the danger, but with prepared facilities and place to work with it, it is doable.

Though, I won’t be bothered with alarmist mentality of every nook and danger of anything one should and should not do, and contemplate later with other dangerous materials working with KCN, which is an option of one to work with in fixing the image.

Just do your work safely. If you have the knowledge, apply it.


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