A friend and I are thinking of building ourselves a Hotbox for waxing our skis using the following specs (http://www.nordicskiracer.com/cgi-bin/news/news_item.asp?NewsID=448).
- Have any of you done this before?
- Is it a good idea to Hotbox skis throughout the season?
- Is this a good investment?
No, I've never built one myself, but I have been thinking about it for a few years. I just don't have room for one unfortunately.
Are they a good investment? Maybe. Depends what you are looking for exactly. For general training and ski storage I just re-wax with Vauhti shop blue. The less hard bulk blue. It's a good training wax and is gentle to the skis as it melts easily and scrapes off without chipping.
The main use for a hot box is to quickly re-saturate the base with soft wax after you've stripped all the wax out somehow - cleaning, stonegrinding, metal scrapping, etc.. I think it's probably a good idea to strip the wax out and hotbox skis at some point in the winter if you use lots of fluoro powders. I wouldn't say it's as necessary if you only use hydrocarbon (CH) waxes. The application of fluoro powders with an iron will ineviatebly damage the topmost layer of p-tex base and prevent further wax penetration, so hotboxing would be a step in clean them up and getting them ready to accept the next race wax application.
A simpler routine we use regularly in our typical race waxing routine is 4 layers - the first 2 (regular Vauhti blue and Spektra or Speed) are simply clean-up and prep for the final coats of fluoros. This works too, so does regular waxing after skiing. What's really nice is a ski centre where you can show-up ski and then wax right away afterwards. Hard to find in Ottawa thus far, but Relais Pleine Air and Nakkertok are getting there!
There are 2 things you really need to worry about when hotboxing - what the temperature of the ski is (and how to control that) and what wax you use. You'll want to read this - http://www.caldwellsport.com/Heatbox.htm. Then make sure you really control the temperature well before subjecting your skis to it. Now the wax is going to be really-really soft, and should be free of any Silicone! Zach Caldwell uses Star Uniblock Yellow, but I think the Vauhti Base Prep Orange would be excellent for this purpose as well. Since it's going to be a really-really soft wax, you're going to need to properly prep your skis with blue or green before using them most of the time. No big deal, but you have to remember to do it, and it might actually add to your prep time for each ski. I usually recommend 2 layers of purple before skiing on the skis at -2 to -5C or 3 layers of blue/green for colder temps. Even then you might need to ski them in a bit. You would have to plan strategic times to hotbox them.
Hotboxing can shorten the life of your skis. It will dry them out. Remember It's sort-of akin to kiln drying wood (http://www.ca.uky.edu/agc/pubs/for/for55/for55.htm) ..do it too much or too fast and the wood will crack and split. This happens to skis too. More common is the bases get convex or delaminate as the glue dries. Ski camber can soften as well. (There are some coaches who have skills at changing ski cambers using saunas or hot boxes, but I would recommend selling the skis and finding a new pair that fix than messing around like that! )
So the short answer is you really have to be careful. But I think there's lots of good info and designs out there and you might find them useful from time to time, but not as a way to avoid having to prep skis for the weekend unfortunately.