Reading the explanation on one ski shop's website advocating hotboxing of skis to enhance wax penetration, I can't help wondering if this is yet another lucky rabbit's foot to help people feel faster.
According to a Peltonen tech rep at a ski tech seminar several years ago at Great Glen Trails in New Hampshire, under the best of circumstances wax only penetrates about two THOUSANDTHS of an inch into sintered base material. Maybe three, but what's an extra thousandth of an inch among friends?
The hotbox promo goes like this: heat your ski to 55C (131F) for 6-8 hours with a warm wax on there, then do a coat or two of something rated for a skiing temperature of 10-21F and it's equivalent to 25 waxings! The unit cost for this service is much less than if you had the friendly wax grunt actually do 25 waxings. It is slightly less than we charge for a new ski prep using iron, scraper and brushes.
Why not just blow some Swix CH10 or BP99 on your own skis and then lean them up by your furnace for a couple of days?
Racing is such a neurotic activity. How many of the processes related to it have sprung up just because someone with a pack a day habit and a shop apron figured out how to exploit that? A confident racer is a happy racer. A happy racer is a fast racer. At least you want any anger and aggression to be directed up and away from the racer's equipment and support staff. Assure them they're on The Good Stuff and then tell them what that other racer just said about them. Arrgh! I'm a stone ground, hotboxed killin' machine!
Hard waxes for cold conditions melt at higher temperatures than soft waxes for warmer ones. Thus they do not penetrate as easily into the base. But their job is to condition the running surface of the ski to withstand the drag and abrasion of icy conditions in wicked low temperatures. As such they're more of a surface treatment than the softer waxes, which need to saturate the base material more to assure that free water is excluded. Those soft ones melt readily under a moderate iron temperature. You may realize some gain by stuffing your skis in a hot crevice for a few hours, but is it worth what the tech wizards need to charge you to pay for their time and the loan they took out to pay for the box?