Sintered Ski Base Density

Pretty sure with K2,
Domain, Sight, Press all use extruded.
Iron Maiden, Fujas, Pettitor and Hellbent use Sintered, I don't know what sintered though.

So I bought the K2 press at the end of this last season and I could swear that they listed on their website that it was extruded, but now it just says "swapbase" which doesn't tell you anything about the base material used.

as a general rule of thumb the higher end skis of a company are going to have sintered bases. the press is more in the range of a price point ski and as such has extruded bases this year and last. i've already made my point in that when i look to buy a ski i take as much into account as possible so i make the right decision for me, and when a company doesnt tell me about their ski im less likely to go for it as its a serious purchase and (in my case) will last 3+ seasons. I dislike the trend of less info to sell your skis and will support those who tell me about them. Its not as if the info is particularly complicated, hell there's even videos which explain every aspect of a ski you need to know when purchasing (season 1 4frnt tech talk)

http://vimeo.com/album/176048/video/7806239

Yeah I expected the press to be extruded since it was a cheap ski, but I looked up the tech specs anyways just because that's something I like to do. K2 definitely used to identify their skis as being extruded or sintered but now they no longer list that info in their product descriptions...

Don't believe it.  The UHMWPE sintered will take up wax because it has voids in it.  The "plastic" itself does not absorb anything.  You need to get a lesson in sintering.  These plastics can be used to filter fluids by passing the fluid through the plastic.  If that's the same study I saw before it's only partly true.  A sintered base holds wax in the voids, then it bleeds out as you ski.

If fact a sandwich ski with UHMW sidewall will benifit from waxing the sidewall.  It's just like the base.

K2 will not reply to an email.  I did find that a Swap Base only means that each pair will have a different base design, or color.  I boxed up the pair.  They did seem to take some wax, but not a lot as a race ski would.

I thought I already mentioned this, but I guess I didn't. In all of our commercial sintered bases we use a 7000 series p-tex. This allows all of our sintered base skis to be super fast, ultra durable, and deliver the best performance possible.

http://primateriasport.se/PDF/Peter_Sturesson_examensarbete_skidfriktion.pdf - EXTREMELY long and full of scientific crapola, BUT:

See pages 19, 20, around there - electron microscope photos of sintered ski bases.

It was established by that other thing I linked to that any porosity in the base (or voids in the sintering) was of a diameter less than that of a molecule of water. A water molecule is much, much smaller than a wax molecule. Wax bleeding out of a base sounds more like ski-tech-guff to me.

Again I will tell you that study is not totally true.  You are not going to see any "pores".  It's more like a piece of paper.  There are fibers.  Inbetween the fibers is where the wax goes.  You more than likely have extruded base anyway because you don't know much. 

Anyway dirt will slow you down, so keep 'em clean by brushing.  Then don't use any base cleaner is best.  Swix Glide Wax Cleaner is different.  It will not remove wax or dry the base.

I likely have extruded bases? What a ridiculous assumption to make, and inferred from entirely questionable logic. Just for reference sake, my day-to-day quiver currently comprises 2 sets of skis, both of which are sintered.

Besides, if you possessed even a relatively simple of physics, chemistry and basic geometry you would see that your argument is stupid. Bases are like paper with fibres? What the hell are you talking about? Did you even look at those electron microscope images of base material? That's not like someone having a look through a magnifying glass. If you look at an SEM image of a piece of paper you can see the massive fibres. Look at those base pictures again - they're just not there. Nor are any "pores" or any such thing.

There is physically not enough room in the molecular structure of the base material for a singular molecule of wax (a rather large complex hydrocarbon) to fit in there. Remember that water is a considerably smaller molecule than the hydrocarbons in wax - if ski bases possessed the supposed porosity you're crapping on about then they would absorb water a lot easier than they take on wax. All that is possible to achieve is adding an external layer of wax to the material.

Your earlier comments about the wax "bleeding out" are farcical. Where is this wax supposed to be? There's nowhere for it to go, apart from this very fine surface coating.

tl;dr: Are you serious? You're an idiot.

Having just spent the time reading the article it is not stated whether the material in the SEM images is sintered or extruded it just simply says its a base material from Fischer with no reference so could be either. The article itself was an interesting read and as somebody from a science background with an interest in getting into the ski industry was a nice piece of knowledge gaining. Has there been any follow ups to the article? I'm on mobile so not really in a position to check properly.

So you have high quality sintered bases but you don't wax them?  The people who produce sintered bases do testing to see how much wax is taken up.  It's measured in micro grams per sq. cm.  I good base depending on size of course, will hold about 3 grams of wax. 

True that grinding a base can cause creep in the plastic where a sharp scrape to shave off base plastic may be better to renew a "dry' base.  I do it all the time.  Then instead of grinding, I structure with a stiff stainless steel brush.

Don't take it personal, I just am saying that that "study" is only part true in a few places.  The rest is pure collage boys who don't know what they are even doing.  Like the one guy said.....experience will tell you what goes fast, and what not so fast. 

I hot box skis.  One can tell real easy if they "take" wax or not.  A good sintered base after a few days of skiing fast will still look oily, and shine after a post skiing brush out.  An extruded base will not "take" wax, so it will look dry very quickly.  Once a sintered base is skied dry it becomes burnt, or "hairy".  That makes it slower.  The only way to fix that is to either grind away the burnt surface, or scrape it off.  One must do a long base bevel prior do doing either so the edges do not interfere with the scrape or grind.

Bla bla bla.  Don't wax your skis etc. 

Theres been a lot of discussion around it on TGR but not much done in the scientific space in direct relation to it.

Further parallel research and scientific/engineering papers conclude similarly though. Mostly the conclusions, summarised, were that wax does reduce friction and increase glide but only due to a combination of surface film adhesion and smoothing/filling of "large" (on a microscopic scale) base imperfections, and that the effect is largely lost with a few thousand metres of use. Repeatedly the concept of pores and absorption of wax is debunked - even one of the men named in the patent for ptex has said that there are no pores in press-sintered uhmepe base material, and it is a myth perpetuated by a combination of the wax industry and hearsay (if enough people say it, it must be true right?)

A group of researchers (I'll see if I can find the article again, Engineering in Sport 7 Vol.2 pg 136ish I think) found that they could get wax to combine with base material but that was through immersing a block of ptex in a bath of wax at about 120c for 4 hours and even then they observed that what they got was actually a lump of ptexy-waxy goo that was considerably softer than the original...

So yes, there is merit to waxing, particularly for racers where the course is sufficiently short as to not exhaust the film of wax on the surface of the skis... but magical base reservoirs excreting wax? I don't think so.

Have you ever hot boxed a sintered base ski?   I heat to about 150 degrees F.  I have taken the same exact skis (I do multiple skis for Oregon Adaptive Sports)  The few that I only used an iron on did not hold out at all compared to the ones that had been hot boxed.  I have been doing ski service for several years.  The proof is in the pudding.  Now back to work.   Maybe this might help you.  The videos are a bit long.
http://www.youtube.com/watch?v=4_ccScQr90Y&feature=share&list=PL7726E76AA2EDD1AD

Take care man!

Liberty also lists their base materials. Plus a good amount of other tech-y specs.

So Onenerdykid mentioned Atomic uses 7000 on their skis which seems pretty high especially when brands like Moment and ON3P take pride in their 4000 bases. (I havent checked, but i dont think atomic lists their base specs so why dont they brag about 7000). So the question is are the # ratings standardized across base suppliers? How is the density measured as in where do these numbers come from? 2000, 4000, 7000 what? What are the units???????

I agree with you that we should list our base materials, and I've told the ski guys the same. But, the reality is that this kind of information would go over the heads of at least 90% of the skiing population, which is why they keep it out. I still think they should add the info to the catalog/website as it doesn't take up any space really, but it's their call. I will keep pushing.

BATALLA Skis—4100 durasurf "sintered" by Crown 2.5mm. thick on Park Reapers & Spriggs Pro; 1.8mm. on All Mtn Twins & Powder King.

Interesting thread.

onenerdykidI agree with you that we should list our base materials, and I've told the ski guys the same. But, the reality is that this kind of information would go over the heads of at least 90% of the skiing population, which is why they keep it out. I still think they should add the info to the catalog/website as it doesn't take up any space really, but it's their call. I will keep pushing.

The super easy info on Atomic is we either use extruded or P-Tex 7000. That's it. Extruded is mainly reserved for kid's skis and rental specific stuff, while we use the 7000 hotness on 99% of our adult skis, including the Infamous and Punx. From all of our testing, it just makes the skis ski so much better when we invest in a 7000 series base. It is more expensive on our end, but it just leads to better skiing skis.

Whatever keeps the pimp hand strong.