I made these last night using isomalt and filtered water. They looked fine until today. They look like they crystallized over night. Has this happened to anyone? Can I fix it? Did I do something wrong?

I brought the isomalt up to 330 then pulled it off the heat. I added the gel coloring when it cooled to about 300 and stirred until it completely stopped bubbling. I've never had this happen before.

Sorry, no photo.

Better to NOT stir in coloring UNTIL the bubbling has stopped. 

Shock the pot in cold water to stop temp from rising, add color, allow bubbles to dissipate without stirring, stir in color.  By doing it this way, the bubbling action helps to evaporate the water from the added color.

You may be able to make them look better by torching them lightly--unless they are very thin.  If it's true crystallization, it will be all the way thru and torching them won't do a lot of good.

AHmm... I don't think it was the food coloring. I wound up melting the bottle again and getting the temp up to 350. So, I would think, any water should have evaporated at that point. The 1st bottles had dull patches with crystals all over them. The 2nd ones looked fine, but after a few hours dull spots started to form in patches. I put them in airtight containers overnight. That seemed to stop whatever is going on. The dull patches are still there though. I just hate to think I'll have these on the cake and they start to crystallize while my client has them. Thanks for the help though!

Well, yes, of course once re-melted, any water issues would be resolved. 

I will say, however, that 350 is extremely hot for isomalt, especially if no additional water has been added.  At that temp, it can essentially scorch (especially that which has been in direct contact with the pan sides and bottom) and then become temperamental. 

I'm sure that the client will be impressed with the bottles, even with a few minor imperfection.

Fortunately, it did not burn. I had another person tell me the same thing happened to them. They were told it was due to over-stirring and the color should go in while the sugar is cooking and still bubbling to help mix the color in, hence less stirring. So, I guess it's one of those things you find what works best for your own situation.

Thanks for the help. The cake has already been picked up and my client was very happy.