Does ski base material contains pores?

[Beo81]

I got an answer from Swix. I also used google translate on a Swedish test-report. Sadly google translate had problems with the test results, but the introduction and conclusion should be readable.

Google translation: http://translate.google.com/translat...df&sl=sv&tl=en

Original document: http://hem.bredband.net/stefansand/rapport.pdf

In the answer from Swix they have made tests on 3 pair of skis. In all cases they found that waxing glides better. It is a bit embarrassing by Swix to make such a report, because it only states what Kuzmin already discovered: Initially a waxed ski will glide better. Not by much but still better. After some distance the waxed ski will begin to slow down due to dirt accumulation. The Swix test was done in a small slope, and the skis were cleaned after each run. They did not test this properly in other words. I am still shocked how the waxing companies are dealing with Kuzmin-principles. But ok, they showed us what Kuzmin already said in his thesis.

In the Swedish report all tests are in favor of Kuzmin after a certain distance, except one where they had the exact same glide. They even discovered that the difference was much lower for higher speeds.

The conclusion to this should be that steel scraping is a very good alternative to wax. Unless you re-wax your ski after each run, steel scraped will be faster as well. So taking in mind that steel scraping is much easier, cheaper and needs less maintaining it is obvious that steel scraping is a very very good alternative. In some conditions you may even have better glide all the way with steel scraping. Steel scraping may also be an alternative to stonegrinding.

I agree with the conclusion in the Swedish report.

[scottland]

The producers of UHMWPE says the following:

Regarding "porosity" in UHMWPE skibases:
There are no "pores" in press sintered UHMWPE as some wax manufacturers tell the people
since 40 years.
(I guess the "pore-myth" comes from long ago, when ski had no PE base and the gliding area
consisted of the wood the ski were made of.
Wood is indeed porous in structure, so the wood cells (pores) could be filled with wax)
Back to UHMWPE: As stated no "pores" are in the material.
The mechanism of waxabsorption in UHMWPE is simple: By bringing the UHMWPE base
material in contact with hot wax ( Paraffin) this "low molecular PE"
goes into solution in the amorphos regions of the amorphous/crystalline PE.[as the old
chemists said: "similia similibus solvuntur" ].
By cooling down the skibase (on snow) there is a tendency of the wax to migrate out of the PE matrix as the solubility is a function of temperature.
I am working in R+D of skibases since 38 years and as stated above, have never seen a
"pore" in UHMWPE, but false theories are unfortunately longliving!!

Did you understand what this meant?

"similia similibus solvuntur" means "like dissolves like" roughly translated. Basically paraffin is a form of polyethylene, so heated amorphous paraffin is dissolved(poor word choice) into the UHMWPE base.

Yes, UHMWPE does not have pores, nor is it porous, but it does 'absorb' Paraffin wax.

That info right there completely contradicts about half of the beliefs in Kuzmin's paper. And it came directly from a chemist that works with UHMWPE

[highangle]

^^i think Kuzmin addresses this and terms it as the wax 'dyes' the base to a depth much shallower than the average dirt particle

neither he nor the waxmakers have said much about the properties of the resultant compound of the esters of wax and PE, however microscopically thin it may be

it was likely well beyond the scope of the paper and his budget

[highangle]

Just a comment on this, since I've done some work on measurement theory. Doing a measurement "in a rigorous way" is harder than you may think. It isn't just "being careful," and contrary to popular belief, using precision instruments doesn't mean measurements are worth a damn. All measurements, from a carpenter's guestimate of a straight cut to a surveyor's laser, have error. Both human and instrumental.

More formally, a measurement is made of a "true" measurement that points at a real physical referent, and error. Error that points at everything from unconsciously moving your hand a fraction of a mm, to misreading the number on the dial, to precision instruments fluctuating as temperature, humidity, or voltage changes. Then there's bias: When you file an edge, do you make the same tiny error the same way each time (systematic), or do you mess up a new way each time (random)? Lot of noise to account for.

So when you publish, you specify your reliability. Eg, how much and what kind of error do your measurements or treatments have?

What kind means accuracy (how close you are to a "gold standard") and consistency (how well you can reproduce the same measurement or outcome over and over), plus the systematic vs random issue. There are standard test-retest methods for getting numbers on all this and then doing a statistical analysis. Let's say that this fellow did all his measurements himself, so no need to assess interobserver error (having different people working on the same measurements). But unless he does reliability tests on his own measurements, and for each of his various base treatments, and for his machines, if they're non-standard, his numbers are hard to interpret.

Well-known research teams, with proven track records and earlier statements of reliability, can get away with just talking about the specific instruments and references to techniques. But newbies have to earn that right by really spelling it out.

You get the idea. Don't worship "careful measurements." They may be carefully wrong. And "superior measurements" may involve finer increments (say a laser instead of a ruler), but still be just as wrong. There is no default position in all this. No one in science takes outcomes seriously unless we know something about the measurements' reliability and applicability. That's why papers have such long "Methods and Materials" sections.

thanks for the primer
i have to agree it's quite factual, and you explain it well within the scope of this discussion
i do think my M.Sc. in geodesy lends me some qualification to measure your efforts, and folks here would benefit by a close reading of your post, because you are not engaging in rhetorical devices or bullshit, just being straight up

is Kuzmin's paper exhaustive or as rigorous as it could be given unlimited time and budget? of course not

if the goal was to achieve the highest level of precision attainable and budget be damned, i would have sought to quantify or at least address any 'personal' sources of error by a different rep/set/time protocol with the human skier against a simple dead weight straddling a pair of skis on alternate runs, as we know that a human is not capable of placing equal weight on both skis continually through the whole run
i would have also used more skiers and weight blocks of varying weights, more reps to a set, more sets, and done it in different temps and snow conditions and on different runs in different geographical locations

i would also have considered the run itself and sought to quantify the quality of the track surface using a laser scanner and a summation or even a Simpson's Rule approximation of coordinate values as a delta from a theoretical inclined plane

a time series analysis of the snow/track conditions at a tight interval during the tests would also have been nice

given time, i'm sure i could have spent a lot of $$ to increase the reliability of the experiment and perhaps lowered the p-values significantly
im pretty sure Kuzmin could too



but the fact remains that these stand as the best available measurements until someone comes along with something better

would you agree?

[scottland]

And 'beyond the scope of his paper and budget' is the important part. He did a very isolated test using a very small spectrum of data with control conditions that don't always represent typical riding. All we can assume from his paper, taking a giant leap of faith that his numbers are accurate is that:

In spring conditions, with exceptionally dirty snow, depending on the wax used, cross country skiers can see improved glide using wax anywhere from the first .3km to 3.8km.

That is about all that we can conclude from his narrow test results.

When someone presents a better report with repeatable results, more winter-like conditions, with data that actually leads to something other than conjecture, let me know.

[highangle]

And 'beyond the scope of his paper and budget' is the important part. He did a very isolated test using a very small spectrum of data with control conditions that don't always represent typical riding. All we can assume from his paper, taking a giant leap of faith that his numbers are accurate is that:

In spring conditions, with exceptionally dirty snow, depending on the wax used, cross country skiers can see improved glide using wax anywhere from the first .3km to 3.8km.

That is about all that we can conclude from his narrow test results.

When someone presents a better report with repeatable results, more winter-like conditions, with data that actually leads to something other than conjecture, let me know.

even better, you could do it yourself and show your p-values
then we would have a measure of how far we could extrapolate the results

[Beo81]

Did you understand what this meant?

"similia similibus solvuntur" means "like dissolves like" roughly translated. Basically paraffin is a form of polyethylene, so heated amorphous paraffin is dissolved(poor word choice) into the UHMWPE base.

Yes, UHMWPE does not have pores, nor is it porous, but it does 'absorb' Paraffin wax.

That info right there completely contradicts about half of the beliefs in Kuzmin's paper. And it came directly from a chemist that works with UHMWPE

Priceless.

Yes. Do you?

Wax adheres. That`s why waxed bases glide better the first few meters. But it soon wears off or even accumulate dirt and become much slower compared to steel scraped. It is not possible to saturate a base or even apply heat to get wax into the base. That is what they are trying to tell you.

You should probably look into what Urs Geissbühler actually means about this before quoting him. Translated from Swedish:

Urs Geissbühler from the world's leading ski base manufacturer IMS Kunststoff in Worb does not find the Kuzmin findings surprising:
"To me he hits the open doors." Glide wax is a relic of the wooden time says Geissbühler. "I think that glide wax mainly works on a psychological level. "

So STFU. If you feel you still need the psychological benefit of wax then please go ahead and wax. Just don`t post shit that you did not think through. .



Mundus vult decipi, ergo decipiatur.

[Beo81]

Here are more tests:

http://translate.google.com/translat...df&sl=sv&tl=en

As posted before. The Swix testing already posted. Sorry for the bad google translation but it should be readable.

[scottland]

Priceless.

Yes. Do you?

Wax adheres. That`s why waxed bases glide better the first few meters. But it soon wears off or even accumulate dirt and become much slower compared to steel scraped. It is not possible to saturate a base or even apply heat to get wax into the base. That is what they are trying to tell you.

You should probably look into what Urs Geissbühler actually means about this before quoting him. Translated from Swedish:

Urs Geissbühler from the world's leading ski base manufacturer IMS Kunststoff in Worb does not find the Kuzmin findings surprising:
"To me he hits the open doors." Glide wax is a relic of the wooden time says Geissbühler. "I think that glide wax mainly works on a psychological level. "

So STFU. If you feel you still need the psychological benefit of wax then please go ahead and wax. Just don`t post shit that you did not think through. .



Mundus vult decipi, ergo decipiatur.

I'm sorry, I can't take any findings from that paper seriously on this note alone:

"Before measurement the hot-waxed skis and dry skis were brushed with a Red Creek steel Rotary (4000 r/ min) brush."

I don't even feel I need to explain why.

[Beo81]

Even if you do not comprehend we are not discussing that paper alone.

[highangle]

I'm sorry, I can't take any findings from that paper seriously on this note alone:

"Before measurement the hot-waxed skis and dry skis were brushed with a Red Creek steel Rotary (4000 r/ min) brush."

I don't even feel I need to explain why.

perhaps you are unaware of the Rule of Charity?

it says that if you are intellectually honest, you charitably allow the most favorable interpretation of a statement made in good faith

the above quoted English sentence may be an error in translation, a misprint, or a misspeak
in other words, there is a high possibility that Kuzmin didn't apply wax and then strip it off in order to measure the performance of the ski while ostensibly waxed

but then again, Scotsmen in general have a wii bit of a reputation for excessive parsimony, so maybe you just don't understand the role of good faith and intellectual honesty in even a spirited discussion?

[Beyond]

given time, i'm sure i could have spent a lot of $$ to increase the reliability of the experiment and perhaps lowered the p-values significantly
im pretty sure Kuzmin could too

but the fact remains that these stand as the best available measurements until someone comes along with something better

would you agree?

With your background, you get the point of good measurement: being able to reject your null hypothesis cleanly.

Hmm. Best available? OK, agree in the limited sense of apparently being the only available using his protocol. So best. Really not qualified to judge what his protocol is worth; as the stat guys say, "garbage in, garbage out." So yep, now someone else who is in the field needs to try to critique/replicate/falsify. Can't judge how "good" his data are in a larger sense until then.

Actually, this thread is good intro to how science works for anyone nerdy enough to wade through it.

[Beo81]

With your background, you get the point of good measurement: being able to reject your null hypothesis cleanly.

Hmm. Best available? OK, agree in the limited sense of apparently being the only available using his protocol. So best. Really not qualified to judge what his protocol is worth; as the stat guys say, "garbage in, garbage out." So yep, now someone else who is in the field needs to try to critique/replicate/falsify. Can't judge how "good" his data are in a larger sense until then.

Actually, this thread is good intro to how science works for anyone nerdy enough to wade through it.

Did you not read my posts? I have posted a lot of critique, replications, tests results. Even given contact details to Primateria, a company that specializes in friction and are co-operating with the Swedish National Ski Team. Read for yourself, everything is posted already.

Btw, Primateria is working on a new report with glide tests. I will probably get a copy and post it here.

[highangle]

With your background, you get the point of good measurement: being able to reject your null hypothesis cleanly.

Hmm. Best available? OK, agree in the limited sense of apparently being the only available using his protocol. So best. Really not qualified to judge what his protocol is worth; as the stat guys say, "garbage in, garbage out." So yep, now someone else who is in the field needs to try to critique/replicate/falsify. Can't judge how "good" his data are in a larger sense until then.

duly noted, particularly with respect to my use of qualitative terms

Actually, this thread is good intro to how science works for anyone nerdy enough to wade through it.

it is, isn't it...the conflict that breeds good science is certainly well represented, and the conversation keeps getting better, to everyone's benefit

thanks for your great replies


Beowulf - keep bringing it! ~4000 views and counting...

[Vorda]

Did you not read my posts? I have posted a lot of critique, replications, tests results. Even given contact details to Primateria, a company that specializes in friction and are co-operating with the Swedish National Ski Team. Read for yourself, everything is posted already.

Btw, Primateria is working on a new report with glide tests. I will probably get a copy and post it here.

I realize you're enthusiastic on this subject, but there's no need to repeat the same statement over and over, at least not to someone who has clearly read the topic.

Also, you should stop using the Swedish National Ski Team argument, I'm sure you know how useless it is in this discussion.

I'm out again

[Beo81]

Vorda, The "experts" are using these principles. Do you not see the relevance? Maybe I should use the Norwegian National Ski Team argument then?

I do think I need to repeat myself when everyone is asking for more tests, peer review and so on... If they read all my links and posts maybe I could stop repeating myself.

Most of you are discussing the Kuzmin thesis alone. I have posted one more thesis and lots of tests, but still everyone can not get over Kuzmin and are discussing only that paper.

Btw, had another good test day yesterday. I had a friend with me and I also prepared her skis. The conditions were a week old powder, but stayed mostly in the pist. Hard pack on top and soft cruising snow at the bottom. -15 degrees Celsius. My skis felt faster than ever before, and my friend was shocked when she found out the same about her skis. We were the two fastest people in the resort. Super fun and super fast.

[Vorda]

The thing is, unless the Swedish/Norwegian team were completely wtfowning the other teams, it really doesn't matter what they use. It's the same as the South-African team using it.

And even then, 99% of the results are the athlete and other gear, not the wax.

Good to hear your results are positive. You guys didn't get blessed by Daisy btw?

[Beo81]

Well, I do belive the glide tests are a result of careful prepared ski bases and not the athlete.

I am always blessed

[GeezerSteve]

And even then, 99% of the results are the athlete and other gear, not the wax.

That is not true for classic XC skiing in most conditions, but we're talking kick wax. Hitting or not hitting the wax is often dispositive of who wins a classic event.

[Beo81]

http://www.wired.com/playbook/2010/0...tories+2%29%29

I am amazed that these guys do not comprehend that ski base material does not have any pores. Inhaled to much fluorocarbon maybe?

[DavoRider]

Thanks for discussion! Found out a lot of really interesting information.
My conclusions:

*Ski base must be totally smooth
*Top layer must be "fresh" (virgin) plastic
*Clean structure must by applied according to weather conditions
*Wax gives lubrication, but for short period only. Wax works for longer if it is disolved into base. That requires heat.
*Heat is bad for "fresh" palstic

This means the best combination is smooth structured plastic topped with wax which doesn't require heat?

By the way. Does anybody know at what angle it is correct to hold steel scraper? Is it 90 degrees in relation to plastic or less? Not sure how does that cut those hairs. It is not the way the ordinary shaver works.

[inthemtns]

Have you read Kuzmins thesis? It´s probably one of the worst pieces of mock science I´ve ever seen. How it can constitute a phd is beyond me. It´s more a collection of unsubstantiated claims and poor understanding of the properties of materials, written in a non-scientific manner, combined with passive-aggressive attacks on wax manufacturers.

I could only get half way through this thing. It is truly awful. His scientific method is poor at best.
Wax makes skis faster.