Last week the SkiPost e-newsletter had this item about the practice of saturating ski bases with wax by the slow-bake method known as hot boxing or heat boxing. The term heat boxing has emerged recently to differentiate the ski prep technique from the pot smoking technique also called hot boxing, in which smoker or smokers indulge their habit in a purposely confined space.
How to Hot Box?
[A reader wrote]"You referred to proper
& improper hot boxing. I have a hot box of my own construction
but I have never seen any real guidelines for how to best use it. I keep
the temperature at 120 - 130 degrees (Fahrenheit) for about 6 hours. It
has a fan that continually circulates the air. How does this sound?"
[Ski Post answered]First of all most ski manufacturers do not suggest skier hot box their skis. [emphasis mine]
an iron exerts heat to the base, the hot box exerts heat to the entire
ski. It can do nothing to improve a ski, over normal waxing done
properly and with patience, but can weaken the epoxy and alter a ski
camber if the heat gets out of control.
That being said many people and ski shops hot box.
To do it with the least risk
The base needs to be open and not sealed so it can accept the wax
easily. (Stone grinding to achieve a fresh open base is another issue)
The max temp at any point in the box should not exceed 55C (130F). Some
boxes have great fluctuations in their temps throughout the box.
A wax with a melting point at 55C needs to be used. Not many waxes are
actually molten at this low temp. They may be soft but they are not
molten. Start suggests Service Wax LF for its unique double molten
points one just below 57 and one at and one at 120C.
4) Melt wax onto base.
Leave in hot box for as short a period as possible. Less than 2 hours
should be sufficient. The base is only a couple of mm thick and will
absorb wax quickly or not at all.
6) Realize this is speaking from the standpoint of the ski manufactures.
7) This is not speaking on behalf of the Hot box and Hot bag manufactures who would argue differently.
I hope this helps.
We try to respond to new information to improve the service we offer at our shop. So far, our research has not turned up any service providers who have cut their heat box times significantly. Many recommend warming the skis for as much as 12 hours. Most agree on the temperature range, averaging 50-55C and never exceeding 60C. According to SkiPost, one should never heat skis as high as 60C, let alone leave them there for 50 minutes to an hour, as some service centers advertise.
Many heat box providers do acknowledge that extended heating can affect some skis.
I was initially skeptical of the heat box compared to ironing. Even when I accepted the idea of heat boxing, it was more as a time-saver and basically harmless rather than outright superior to ironing as some proponents were saying. I still feel that way about prepping new skis. Much of the time spent prepping new skis would have been spent ironing in and scraping off numerous applications of wax just to achieve maximum saturation of the base material.
As with most technical arguments in skiing, there's a lot of opinion and very little real science. Experts apply some general principles based on one or two variables rather than all possible variables and then issue blanket statements. For instance, SkiPost cites the fact that the base material is only a couple of millimeters thick to support the statement that less than two hours of heating should be enough for complete wax absorption. There's no consideration of base density, which can vary with the quality level of the ski, and no supporting experimentation to test whether the wax penetration really is complete. Toko did provide data on wax absorption based on actually shaving down the base material to see how far the wax had gone at different times and temperatures. Another tester claimed to have weighed the skis to determine how much wax had been added by a box versus an iron.
In the end, the statement that ski manufacturers do not recommend hot boxing may come from the legal department rather than anyone in the company who actually skis or develops equipment. If the manufacturer gets behind a procedure that might damage some skis they could face possible aggressive warranty claims. I don't see how it would turn into a very expensive problem for the ski company, since the cases would never involve a big enough damage award to interest much of a lawyer, but why not nip it in the bud? It only takes a short verbal statement to protect the ski company from ANY such claims. So there it is.
All this fog leaves the individual skier and the small shop to decide for themselves about the relative risks and merits of letting your skis get baked. I still lean toward the "mostly harmless" theory.