re-melting rosin
 

When I first started back playing about 15 years ago, I had a few old cakes of rosin lying around that were each at least 20 years old. I put them in a cup, all of them together, cooked them up in the microwave until it was liquid and then poured them into little paper cups, like you get from MacDonald's to put your ketchup in. Then I let them harden and used them as needed. This was mainly a mix of Swedish, Pops and Kolstein's. I used this for a year or two before buying new rosin.

Two nights ago at rehearsal I pull out my rosin that I packed in that cover a week before and it was in pieces. I put them all back in the container, this is Nyman's rosin.

Tonight I brought it home to melt down in the microwave and get it all back together again. I guess I dropped the cake last week and didn't re-open it till this week. I pulled off the foil first and put it all back in the plastic round box. I started at 15 second just to see what it did and nothing. So, I did a minute and half way through. PooF..:eek:
Flames in the microwave. :(

I stopped the 'cook' cycle and pulled it out. The rosin was just about liquid but, the gold paper label on the plastic case must me metal because it burned in a quick mini flash fire and partially melted the plastic under it. So, i peeled off the rest of the label and finished the cook. Now it's cooling off. I might pull out the rosin once hard, turn it over and melt it once more just to make sure it's well mixed.

So, before you melt down your rosin pieces or mix the old cakes together, make sure there is no metal, foil or metallic labels. By the way, I watched they the glass door with a flash-light on it the whole time. ;)

I've done this before, experimenting with a few different combinations of rosin scraps. Made some nice messes, but finally had good luck melting it (gently) in a cup made from aluminum foil over a little alcohol lamp, then cooling in the fridge. Before it gets really hard I peel off the foil, re-warm a bit and wrap little bricks in parchment paper (like you use for baking - it's silicone coated paper so it peels off cleanly). Works great. And why rosin always comes in round cakes I can't figure out; bricks work a lot better! ;)

Knowing that rosin is reactive, when my cake of rosin starts to get hard and brittle, I also use the microwave...but only about 10 seconds at a time until slightly softened, then quit. Fortunately, I've never had to re-melt pieces of the cake back together again. ;)