The fastest solvent I have used is Trichloroethlyene.  An alternative is
National Diagnostic's OptiClear-W

>
>> From: omsuwal@gmail.com
>> Date: Wed, 8 Dec 2010 11:07:45 +0900
>> To: mems-talk@memsnet.org
>> Subject: [mems-talk] How to strip off Apiezon (Black) wax?
>>
>> Hi friends,
>>
>> I wonder whether some of you have used apiezon (black) wax on Si wafers. I
>> applied on a silicon surface to protect the surface while wet etching. I am
>> trying to remove the wax in easy method. I would be glad if someone knows
>> the easy and clean room friendly method to remove the wax from Si surface.. I
>> have tried the following methods:
>>
>> 1. Boiling acetone / Methanol / IPA - It takes very long time and cannot
>> remove well.
>>
>> 2. Piranha solution - It removes well but produces lot of unpleasant fumes
>> and contaminates the labwares. It is no problem if wax is little amount. (
>> but I applied on a whole 4 inch wafer)
>>
>> 3. TCE ( I hate to use TCE).
>>
>> Any other methods are acknowledged.
>>
>> Thank you
>>
>> Om