I've recently started using a different supplier for my white couverture (Agostoni).When the chocolate is in temper, the viscosity is too thin to coat enrobed items (especially weak on outside corners). I've used a touch of additional heat & cocoa butter to thin down overly viscous chocolate before, but have not encountered the opposite problem.
Does anyone have any suggestions for how to thicken overly viscous white chocolate? Will the addition of more milk powder do it? Anyone with experience?
Opposite of thinning: reduce temperature for a while. It will shorten your working window as the chocolate will continue to thicken, but that sounds like the only viable alternative. Adding more solids would require re-refining.
I usually have the opposite problem with white. I have to add cocoa butter to thin. As Cheebs says, cool it more. If that doesn't work, if you have much humidity, it will naturally pick up moisture and that will thicken it.
My experience is that white chocolate is either too viscous or too thin, so I've found it best to mix my own blend from two brands, one very thin, one more viscous. This allows me to modulate when thicker is better (ganaches) and thinner is better.
I would think adding milk powder would be disastrous. You'll just have a clumpy mess. One option is to "over temper" the white chocolate. Over tempering is usually a bad thing because the risk of fat bloom is pretty high, but maybe with white chocolate it won't be as noticeable. To over temper, assuming you're using some form of seed method, you'd leave the seed in longer (i.e., not remove it immediately when below 90 F), keep the mass at the lower end of the working range, and keep stirring/agitating for longer than usual. Eventually excess crystallization will thicken it. The problem will be, however, that the viscosity will decrease fairly rapidly, so you may have a good flow for a short while, then it will just be too thick.
Thanks so much for all your thoughts. I keep the humidity lowand relatively constant in the shop, so I'll try over-tempering. I'm running it in a Chocovision Rev Delta, so it is automatically heating up to reduce over-crystallization every 65 minutes or so--but perhaps I'll have a long enough work window. If this doesn't prove successful, I may have to go back to my prior chocolate source (and possibly try a blend). I appreciate everyone's thoughts. I wasn't sure if I might be overlooking an option or technique. If anyone else has any further ideas or experience, I'm still open. Thanks to you all.
I think that if you reduce temperature you'll have problems with the cocoa butter separating and it may become oily. I feel that the blend idea is best. But having said that, blending between suppliers has proven "interesting" for me. Can elaborate if you want