Please, tell your opinion on our coin cleaning process, did we get it wrong?

​You know far more about coin cleaning and preservation than any of us that put the document together. That is why your input is very important.

Worth noting the cleaning of the coins is not being done to increase their value, but for a more significant purpose. They are being cleaned so they can be better presented in a museum, which will use them to help illustrate a part of Thailand’s history. In cleaning we hope to make the coins as visually appealing as possible, while preserving elements of their age whenever possible.

 
GENERAL NOTICE ABOUT COINS BEING CLEANED

- Process not yet started, just documented based on hours of research, and limited testing.
- Over 100 coins both ancient and modern coins.  Made of silver, copper, lead, and bronze (no pod duang)
- Cleaning is not for any type of grading process or grade enhancement.  Several coins are coming from slabs.
- Cleaning is not for any type of increase in value, nor any issue with a decrease in value. Just care about visual damage.
- Reason for cleaning is to visual display as close to new from 2 to 3 feet away, and when possible keeping elements of any patina.

PROCESS TO CLEAN COINS

Equipment Needed:

1. Industrial 100% acetone (must be pure, not nail polish remover)
2. Distilled water (automotive store sold as battery water)
3. Antistatic tweezers (must have all black tips)
4. Powder free latex plastic gloves (important it be non-powdered)
5. Eye protection (splashes from acetone can happen)
6. Facemask (n95 if your worried, otherwise typical hospital mask)
7. 3 shallow plates (½” lip, glass/porcelain, no color/design)
8. 7 large bowls (4”w  - 6”h, glass/porcelain, no color/design)
9. 1 small bowls (2”w x 3”h, glass/porcelain, no color/design)
10. 1 soft cloth (glasses or automotive microfiber drying cloth)
11. 1 polishing cloth (purpose built cloth for polishing all types of metal)
12. 2 small towels (glasses or automotive microfiber drying cloth)
13. 6 large towels  (automotive microfiber drying cloth)

DAY 1 - 1 shallow plate

Step 1:

1. Fill the shallow plate to the top with distilled water.
2. Put the coins into the plate.
3. Make sure coins don’t touch each other.

WAIT 2 DAYS - 2 large bowls, 1 large towel, 1 small towel, 1 shallow plate
 

Step 2: 

1. Remove a coin and rinse it in a large bowl of distilled water.
2. Simply move the coin through the water, do not rub the coin.

Step 3:

1. Rinse the coin again in a new large bowl of distilled water.
2. Place the coin to dry on a clean large towel.
3. Pat dry the coin with a small towel from the top.

Step 4:

1. Fill a clean shallow plate to the top with acetone.
2. Place the coin on the plate, ensuring coins don’t touch each other.

WAIT 1 DAY - 1 shallow plate, 1 large bowl

Step 5:

1. Fill a shallow plate and a large bowl with acetone.
2. Rinse the coin in the large bowl of acetone water.
3. Place the coin turned over into the new shallow plate of acetone.
4. Make sure the coins don’t touch each other.

WAIT 1 DAY - 2 large bowls, 2 large towels
 

Step 6:

1. Fill a large bowl with acetone and fill a large bowl with distilled water.
2. Rinse the coin in the large bowl of acetone water.
3. Remove coin from acetone, rinse in a large bowl of distilled water.
4. Place the coin onto a towel.
5. Once all coins are on the towel, cover them with another towel to dry.

STEP 7 & 8 CAN DAMAGE COINS - TEST 1 COIN (can do 7 & 8 or just 7 or 8) 

- 1 small bowl, 2 large bowls, 1 small towel, 3 large towels, 2 soft cloths

Step 7:

1. Put the coin into the liquid cleaning solution in a small bowl.
2. Move the coin through the solution, do not rub the coin.
3. Rinse the coin in a large bowl of distilled water.
4. Place the coin onto a large towel.
5. Pat dry the coin using a small towel.

Step 8:

1. Apply the lotion cleaning solution to a soft cloth.
2. Rub the front and back of the coin with the soft cloth.
3. Rinse the coin in a large bowl of distilled water, do not rub the coin.
4. Place the coin onto a large towel to dry.
5. Once the coin is dry, use a polishing cloth to buff the surface to polish.
6. Place the coin onto a large towel.

WAIT 3 DAYS TO SEE RESULTS OF TEST COIN BEFORE DOING ANY MORE COINS
 

Some obvious problems:

1. Assuming the same process should work for coins of any metal.
2. Not specifying what “cleaning solution” you are using.
3. Only waiting three days after buffing. Take two similar coin, buff one, and wait years to see if you made a good choice.

One method that fits all is not the way to go about it. If these coins are important enough to be placed in a museum simply collaborate with curators and preservationists at other museums that have established methods of addressing these issues.  Everything depends on exactly the type coin and it's composition and exactly what issues needs to be addressed on that coin. Sea salvaged, verdigris, and a myriad of other problems that we can only guess at. Different methods for different coins with different issues. Each coin is unique and must be addressed as such.

harryg

One method that fits all is not the way to go about it. If these coins are important enough to be placed in a museum simply collaborate with curators and preservationists at other museums that have established methods of addressing these issues.  Everything depends on exactly the type coin and it's composition and exactly what issues needs to be addressed on that coin. Sea salvaged, verdigris, and a myriad of other problems that we can only guess at. Different methods for different coins with different issues. Each coin is unique and must be addressed as such.

Great feedback, we have talked with local experts.  Sadly the answers they came back with might not be inline with keeping the grade, vs keeping them looking good.  Seems to be a odd balance, curators that are looking to show age and patina, and others that want flashy shinny objects, we kind of want to be in the middle.  We did get some great tips on how to care/store the coins, it changed a lot in how we display and build our displays, had to redo them all and move lighting and them so no direct sunlight on anything.

Agree on each coin is different, that also why 6/7 is undefined in terms of what is used, as we have gotten and tested some from the experts, and some work only for 1 metal and not others.  Our biggest concern is the 1 to 6, and if some grace of God something has the magic bullet for 7 & 8 that would be amazing.  But 1 to 6, we hope gives a good results, without any damage to the coin/grade/value.  We had heard about 1 other chemical people use after acetone, but not enough, can't remember it, think had x y z in its name.