cords on chocolate bars:(

06/02/10 08:38:04PM
dear joe,

I'm really frustrated today.
I've been tempering chocolate many times, I've made chocolate bars and truffles.
but today, for the first time all of the chocolate bars ended up with weird cords on top - the part inside of the mold, means the top of the bar when turned around, turned out nice and with a brilliant shine to it.
but the upper part/ the bottom of the chocolate bar had all these whitish lines on it...
since we were using coberture without any cocoa butter added, we added some. first. 10%.
since I thought that could be the cause for the problem, I lowered it to 5% in the next batch, later made an intent without any cocoa butter added. no real difference.
tempering was as usual, on marble slab and within the indicated temperatures.
what I suppose now is that maybe the cooling process has not taken place properly?
it's been a rainy, humid day today, around 18C. I dont have any proper cooling device and didnt want to use the fridge, for the risk of condensation.
so we cooled the bares just at room temperature.
before, I used to work in a air conditioned working space. so this is a difference.
also, I am now at 2800m - any confluence between altitude and tempering chocolate!!?
I would very much appreciate your answer.
thank you, sibylle