I just found this post, so a I guess I got my answer. Not pretty :-(
Originally Posted by Scalce
SkiDoc(Mike) gave me an answer as he just gave me my tuned skis today.
The grey is base material from my dumbass burning the base alittle.
Guess I need to go easy on the iron.
Whenever your plexi scraper feels like it is dragging along the base, that's what indicates that you have burned it. It's at that time you'll notice a dark residue in the scraped wax. That is polyethylene that has been melted.
First price skis generally come wth cheap double sint or extruded bases. Both types of base offer very little wax absorption, but relatively high durablity.
Sintered bases are generally found on mid- price point skis on up. These bases are generally manufactured by a company named IMS in Switzerland for just about all ski manufacturers. They produce molecular density's ranging from 2000(fastest/most fragile/most versatile/most expensive) to 6000(hardest/least porosity/least fragile/least versatile).
Most of you probably have either 2000 or a fairly recent developed Okulen 3000 type bases. 3000 is not as expensive as 2000, but shares many of the same properties regarding glide and versatility.
Hot waxing is a very involved procedure. One must understand that it is heat that bonds skis together during their construction, and it is heat that will take them apart as well.
Use lots of medium hard pure hydrocarbon waxes for good overall base protection and glide versatility, i.e. Dominator Zoom All Temp, or Swix CH7. Obviously there are other waxes available that are also great. All paraphins are wrought from the same chemical family. So mixing different wax companies are not an issue.
Anything metal residing under the base attracts heat, i.e. titanal, edge matrix, etc. These materials will conspire with your iron making it very easy to burn polyethylene. Rub wax on the base first, then melt two fat rivulets of wax near the edges. 3-4 continual passes max, tip to tail or tail to tip does not matter. Iron temps should be around 120 to 130 degree celsius. First pass is slow looking for an even melt. Successive passes become faster. Always use an upward pull on the iron to suck the wax under the iron base plate . Too much wax dripping down the sidewall indicates too much downward pressure, and will over-disperse the wax and encourage base burn.
When you feel the iron suck down to the base, this indicates it has been burned. It is not irreparably damaged, and it can happen to the best of us.
When a sintered base has been burned, it means the pores in the base that are there to absorb the wax are now closed. Over-waxing with excessive heat or improper technique will effectively narrow the range of temperatues and snow types the ski can run in. This generally leads to a colder range.
2000-3000 bases are formulated to work in warm and cold temps.
A burned base looks multi-pigmented. Indicated by grey and dark black shaded areas along the running surface. The only way to remove this is to have the skis stone ground in order to reveal a fresh layer of base. Always make sure the wax you are about to melt is free of contaminants, i.e. filings, dirt etc, as they will scratch the base. Also, always make sure the base plate of the iron is clean and kept freshly sanded with 220-320 grit paper. This helps create a little structure in the base plate and encourages wax dispersion.
Always use a burr-free super sharp plex-scraper. Race Werks sells 12" Strawberry files, they are the best. Mount this to a bench surface and use it often. A good sharp scraper will only enhance smoothing out base structue during the scraping process.
Unless you are racing or trying to set speed records, use a nylon or brass brush to remove excess wax. You generally want to keep whatever structure is in the base, open for optimal glide. Anytime you see wax standing on the base it will create drag. A little bit is no big deal unless you're as anal retentive as I am. Finally, finish it out with a horsehair brush using a back and forth motion until the base is bright and shiny. Back and forth brushing is not to be done with nylon, brass or steel brushes for obvious reasons. Except when employing specific structuring techniques designed to enhance a specific stone grind structure. That is a whole other story.
Hopefully I have not bored you all with TMI. At some point, I will discuss the often misunderstood merits of rubbing paraphins on bases.