"Charles P Lamb" > wrote in message >...
> Is stirring needed for tempering or is it only to ensure an even
> temperature?
>
> Charles P. Lamb

Yes, if not you will get an uneven tempered chocolate that can
manifest in your finished product.
What ever the technique that you use such as the replacing back the
scraped chocolate that has been supercooled in the marble slab or the
shavings of tempered chocolate ; both of them needs agitation for even
distribution.
Melted chocolates that has cooled down may have an uneven mix of the
different polymorphic crystals( gamma, alpha, two beta primes and
two beta crystal forms).One of the main purpose of the chocolate
tempering process is to seed this melted chocolate mass with a desired
crystal form( precisely the form V beta crystals) for best tempering
results.
Roy