Molding Chocolate

I've already posted this question on the Homebrew Group, but without a response so far. I'm posting it here in hopes that I will get some feedback.

I am still getting fat bloom even after tempering the chocolate. I've tried molding at different temperatures (86 F to 89 F for dark chocolate) and two different methods (lowering temperature of whole batch to 82 F then up to 86F-89F versus taking about 1/3 to 1/2 of batch to cool and seed first then mix with rest), and I do it quite slowly to allow time for the beta V crystals to form.

The bloom appears most heavily on the underside of the mold (where the chocolate touches the plastic). Minor blooming occurs on the chocolate exposed to the air.

I don't get this problem when the batch is poured unto wax or parchment paper, when the molds are pre-cooled or when lecithin is used.

The tempering does work from the standpoint of melting times. I did blind tests with my family to confirm this.

I thought about this long, but cannot figure out why? Has anyone experienced this? Is their a solution?

Here's more info.
- The temperature of the house is around 72 F, very low humidity, winter here in Canada.
- Using organic unsweetened chocolate, cocoa powder, cocoa butter from fermented, unroasted cocoa beans.
- Using powdered sugar.
- No emulsifiers used.
- Using tiny batches of 100 grams or less for experimentation.
- Use a heating pad and a digital candy thermometer which has been tested for accuracy.
- I control the rate of the temperature rising by lifting on and off the heating pad, a glass cup containing the tiny batch of chocolate.