I've been told that there is a species of tree called ironwood
which burns hot enough that wood stove flues are in danger.  I think
the statement that all wood has the same caloric value might be true,
but in my experience, the hardwoods burn longer at a slower rate
making them good for overnight heating in home situations while the
softwoods burn more intensely and for a shorter period of
time.  Kinda like the difference between lighting up a small aluminum
foil pan full of acetone,versus lighting up a small aluminum foil pan
of kerosene.  The last time I lit up a small pan of acetone, there
wasn't much aluminum foil to be found when the flame was done.  Maybe
that's a bit of an over-exaggeration, but you get my drift.....

I've never burned a Presto log, but looked at one at Wally World the
other night and for $4, you get 3 hours of heat according to the
wrapper and spozed to be better for the environmental emmisions.  I
find that the shelter of my Vanagon, my sleeping bag, and maybe a
pouch or two of the "hot hands" stuff(they come in full body sized
warmers these days), is more than enough to protect vital body core
temperatures.  A good Marmot or other brand zero degree bag and
merino wool socks and skivies for base layering will go along way
towards keeping you alive.  Even WalMart has 70% merino wool socks
now for $7 a pair.

DM&FS

At 12:01 AM 11/1/2009, Rob wrote:
>Extra heat? That is the wood burning in addition to the wax.
>All wood has the same energy? Oh wow, think of all the time I spent
>messing with the oak rather than the aspen... See that was my
>problem, I thought I was getting more heat from the oak than I did
>from the softwoods all those years.
>I thought the hardwood burning along with the wax did the trick for
>the extra heat. The only person I know (from a list) who has used one
>said it worked great in the car that had run off the road in a snow storm.
>It  is  one  of  those  emergency things  you  keep
>in  back,  with  any  luck  you  will  never  have  to  find  out  if
>  it  gives  enough  heat  to  keep  you  alive  thru  the  night.
><Shrug> Next time you're messing with a presto log give it a try and
>let us know if it works.
>
>Rob
>becida@comcast.net
>
>At  10/30/2009 08:25 PM,Mike S wrote:
>>At 10:19 PM 10/30/2009, Rob wrote...
>>>At  10/30/2009 06:32 PM, Mike S wrote:
>>>>Sounds much like one of those artificial fire logs. You could
>>>>probably just get one of those, and cut off what's needed, as needed.
>>>
>>>This is a candle gives off 'extra' heat not a presto log.
>>
>>Where does this "extra" heat come from? A special high-calorie wax?
>>Dry wood is around 6K BTU/lb., whether hardwood or softwood.
>>
>>Cutting off a few inches of a artificial log, and stuffing it around
>>a wick in a can (the logs use a soft wax, and crumble easily), seems
>>much easier than mixing melted paraffin wax and woodchips. It also
>>allows one to replenish the candle when needed (a log and some wick
>>are all that's needed). Probably cheaper than paraffin, too.