As some of you know I have a particular interest in Bronze Disease due partly to living in Florida where it is so humid all the time. The catalytic reaction of bronze disease runs faster the higher the relative humidity in the coin’s environment. The rule of thumb seems to be above 50% relative humidity the bronze disease will be active, converting your coin’s solid metallic copper into a fluffy green powder in an irreversible reaction. Below 50% relative humidity the reaction will slow down or stop at low enough humidity levels. Aside from running you AC all year, what can we do to create a dry environment to slow the reaction? One approach is to store your coins in an airtight container with some desiccant packages. But how do you know if this is working? Well, it is possible to buy small digital humidity meters very cheaply now online. I picked up 12 small meters for about $25 recently to do some experiments. I enclosed a desiccant package I had lying around in a Ziploc bag with a meter to see what happened: After several hours, the humidity meter in the bag matched the readings of all the 11 others outside the bag. So, the desiccant package was doing nothing, because it had been sitting out in my house for months and had absorbed enough moisture to match the air inside my house. I wondered if this desiccant package could be reformed by driving off the evil moisture using fire: I piled a bunch of coins and desiccants I had at home onto a cookie sheet and stuck them in the oven at 250 Fahrenheit for three hours. This is a common procedure to dry out coins after cleaning them in water or other solutions and for attempting to slow the progression of Bronze Disease. A lot of the coins I baked are the remains of my July 2019 FUN show activity, “Who wants a scoop of ancient coins?,” which a few Coin Talkers participated in: One interesting thing to note about the baking: the humidity meter died about 15 minutes into the heating process (RIP) but was showing a decreasing humidity level. After baking the desiccant packages, I quickly sealed them in several Ziploc bags to preserve their potency. Repeating the experiment with a freshly baked package yielded this result: It took overnight for the humidity in the bag to fall to this level. I think the absorption process is rather slow, which is a good thing. This means you can handle a recharged desiccant package in the open air for a good while without it becoming completely saturated with moisture. Because the meters are so cheap and small now, I recommend placing them in your coin storage bags and boxes, so you know the humidity level of the environment in which you are storing your coins (especially for bronze coins). You also know when it is time to bake your desiccant packages again. Baking your coins at the same time avoids loading your storage containers with “wet” coins that will quickly saturate your desiccants. I now have these meters in all my coin storage containers and can keep an eye on the humidity levels. What humidity level is safe? That is not totally clear but the lower the better and certainly below 40% would be a good goal. Maybe over time I will be able to observe some results to share. Holiday baking here this year was not all coins. We also made Philipp the Mouse's classic Cinnamon Stars (and other shapes) recipe. Ingredients: 4 egg whites, 1 pinch of salt, 300 grams powdered sugar, 1 tablespoon lemon juice, 450 grams ground almonds, grated zest of an untreated lemon, 2 teaspoons cinnamon. Beat egg whites with salt until stiff. While still beating, add the sifted powdered sugar and lemon juice drop by drop. Put 4-5 tbsp of the mixture in a cool place. Fold in the almonds with lemon zest and cinnamon. Sprinkle the baking mat with ground almonds and roll out the dough in portions, 1/2 cm thick, and cut out stars. Cover the baking sheet with greased baking paper. Carefully place the cinnamon stars on top and brush with the remaining egg whites. Approx. Bake for 20 minutes at 160 ° C. What did you bake this holiday season??? John
Okay, some of you folks must have baked some kind of goodies for the holidays? What is your favorite holiday treat?
