updated by @katie-partington: 04/11/15 03:03:42AM
We are talking 12 degrees Centigrade?
This would be a problem.
On industrial moulding lines moulds (cavity side) are beingheated up to 26-29C prior to pouring in tempered chocolate.
Tempered chocolate will contain a certain quantity of desired cocoa butter crystals. This quantity will be sufficient to act as seeds for the crystailsation of the rest of the chocolate when cooled at the correct speed. Rest of the cocoa butter is still liquid
If you pour tempered chocolate into mould that is too cold liquid cocoa butter forms unstable crystal forms on the mould surface resulting in white areas, streaks and othe bloom.
On a more technical level following happens: when chocolate (containing liquid cocoa butter) contacts cold mould surface heat (energy) flows from chocolate into the mould. This results in the formation of cocoa butter crystals that have a melting point close to the mould surface temperature. Crystals that are formed at teperatures below 28-29C are not stable. Because this process happens very fast there is no time for the correct seed crystals created during tempering to grow and correctly crystalise the whole chocolate bar.
I would suggest warming your moulds up to 26-28C and trying again.
Just jumping in incase someone else has the issue. I just got done dealing with this for about the past year. Was thinking my chocolate skills after almost 8 years were in decline for some reason. Turns out it was just my thermometer.
Sometimes I'd have streaks of lighter colored almost pale yellow on the mold side, and sometimes faint streaks on the back. Problem was it was inconsistent, even though tempering was being done consistently and it was passing the "spoon test" After calibrating my thermometer I found that it drifted from being accurate at 32F but then was off by an inconsistent amount and wasnt accurate again until 233F.
So, new thermometer and validating that it's properly calibrated solved the issue. Now I'm getting consistent temper anytime I try.
BTW: I thought it might be airflow, because I keep cieling fans on in the work area. So I turned them off with no change in temper. Some suggested humidity; but I live in a desert, where if I'm seeing 25%, it's a wet day. But that can also affect things if you're in a humid area. I do tend to keep my molds out at room temp, no heating or cooling of them specifically; then place them in a cold box at around 65-68F on a wire rack.