My rosin is cracked, ways to fix it?!

Edited: March 8, 2020, 10:03 PM · Hi all, yesterday my Andrea Rosin cracked in half and I was thinking ?? how to fix it? Suggestions please! Thanks

Replies (24)

Edited: March 9, 2020, 12:31 PM ·

"I've used a toaster oven set at a temperature below 200°F to reintegrate broken rosin cakes. I have shaped some aluminum foil with a bottle cap, dumped in the rosin pieces and heat the mess in the toaster oven until it looks like a rosin cake again.

When I have bought rosin with "wrinkled" tops I just wear them down over time rosining my bows - it worked fine.

I would not use a flame."

March 8, 2020, 10:39 PM · IF it cracked cleanly in half, you could try warming the freshly cracked surface gently with a hair dryer and push the two pieces back together. Otherwise you can melt it down and remold it.
March 8, 2020, 10:44 PM · Thanks! Will take a look
March 9, 2020, 12:11 AM · How much of a crime is it to melt a bunch of fragments of different rosins together?
March 9, 2020, 5:30 AM · Not a crime at all, but if they really are different rosins with different characteristics you may be surprised at the result. You may hate it or you may love it.

Edited: March 9, 2020, 6:46 AM · I had a shattered cake once and contemplated melting it down, but was warned about fumes, so I binned it. Now I have more than a lifetime's supply, so if another gets smashed, I'll bin that too; although I only have one cake of Guillaume, so maybe I'll have to rethink that one.
March 9, 2020, 9:46 AM · Fumes? Fumes of what? When you melt rosin it smells like pine sap, so maybe you're getting a few naturally-occurring turpenoid compound up your nose. The kind you pay to have included in the formulations of your household cleaning products.
March 9, 2020, 9:53 AM · I was warned.
Perhaps they said it was easy to burn it, and those fumes are to be avoided?
March 9, 2020, 10:09 AM · I've remelted rosin on the stovetop before - the smell was super pleasant. (I also had a window open nearby.)

The rosin behaved differently (was not as supple/sticky) after I remelted it - so I ended up tossing it. Was a neat thing to try though!

March 9, 2020, 11:08 AM · Is rosin like chocolate? In that chocolate is actually in a crystalline state with 3(?) forms, and what form it solidifies into depends on how slowly it cools. If poorly tempered, it ends up as the wrong crystalline form, hence soft dull chocolate with no “snap” so you then have to heat it back up to a certain temperature, and try again.
March 9, 2020, 12:36 PM · Rosemary;
If you follow my earlier advice for melting rosin and mix rosins to melt you might be pleasantly surprised --- or not.
To my mind it is like carefully cleaning your bow hair with alcohol in lieu of rehairing. If it fails to give you the desired result you are no worse off than when you started.
Edited: March 9, 2020, 1:37 PM · Fix it by buying some new William Salchow rosin. :)
March 9, 2020, 3:26 PM · I once melted a broken rosin cake in an aluminum foil-lined form using a toaster oven at 200 F. Afterwards it was indistinguishable in all practical properties, but the color was a bit darker.
Edited: March 10, 2020, 6:37 AM · @Rosemary, my understanding is that rosin is not crystalline. Rather it is amorphous (glassy). Over time lots of such materials will slowly crystallize, so the issue of crystallinity is an interesting one. On the other hand, amber, which is rosin that has undergone geologic transformation (including chemical degradation and polymerization reactions) is still glassy; it is not crystalline.

Most violin rosin is made of primarily one chemical substance (abietic acid), so I don't think different thermal treatments will afford different morphologies. I've often wondered, however, whether rosin is plasticized (made softer) by other additives including water. Heating the rosin to melt it might drive off some of whatever plasticizing substance might have been added, giving a product that seems harder and more brittle -- but that's a guess/hypothesis, not a conclusion.

March 10, 2020, 2:43 PM · I second the Salchow recommendation.

I wonder if a drop of superglue at the base of the broken cake would be sufficient to rescue it.

Edited: March 10, 2020, 7:50 PM · "Doctor, help! My butt has a crack in it!"

Rosin is rosin. I knew a great bass player who literally kept a loose hunk of rosin in the pocket of his blazer. God only knows what would happen if he ever put his coat in the washing machine, but the rosin did seem to work fine.

March 10, 2020, 8:03 PM · I once used superglue to repair a cake of rosin that got dropped, breaking cleanly into two pieces. Many years later it is still in use.
March 14, 2020, 9:09 PM · Wow, Nate, it costs like 100$ ! Isn't a bit too much for a rosin?))
Edited: March 15, 2020, 1:39 AM · It costs about $10 not $100 at most places. I highly recommend it. Made in the USA in upstate NY!
Edited: March 15, 2020, 8:03 AM · $100 is a lot for a cake of rosin. But remember: Everyone on claims they only use tiny amounts of rosin -- "a few gentle swipes, maybe every other day..." is the kind of thing one reads. So if that's true, then your $100 cake of rosin is going to outlast you. For the price of somewhere between one and two lessons, it's probably worth it to have premium rosin. On the other hand, some rosin manufacturers have circumvented this dilemma by putting a fake expiration date on their products.

I use Bernardel. I like it. At the advice of my teacher, I rosin my bow liberally.

Trevor's idea should work fine for repairing a cleanly broken rosin cake. Actually, I thought of the idea before he posted it. But I didn't feel like defending it.

Edited: March 15, 2020, 6:21 PM · Great minds ... ;)
Edited: March 25, 2020, 10:31 AM · Rosemary, It is, of course a federal capital crime to melt a bunch of fragments of different rosins together - There are 10 people on death row, at different stages, as I type - But so far, no one has been executed. Discussions are underway as to which gas to use when executions eventually do take place, but all seem to be agreed that the gas concerned must be rosin-derived, at least in part, because it needs to contain some sort of lethal agent. Think carefully about what you want for your last meal and what music you want playing as you depart this life - I would suggest Rosini ...
March 25, 2020, 1:10 PM · John you aren't even allowed to rosin your bow with someone else's cake if you use a different brand. That's merely a class 2 felony though. You'd probably just do a dime for that.

The Rosini would have be performed by Aaron Rosind.

March 26, 2020, 1:25 PM · Paul, you'd 'ardly 'ear it if the 'air ain' rosind!

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