Kuzmin scraping and structure

What works best and How to

Moderator: Moderator Group

osloskier
xcskiforum 40K
Posts: 252
Joined: Tue Feb 05, 2013 2:28 pm
Location: Oslo, Norway

Kuzmin scraping and structure

Postby osloskier » Wed Feb 20, 2013 3:22 pm

Leonid Kuzmin is a doctor of tribology (i.e. gliding friction). He lives in Sweden and his doctorate is from a Swedish university.

While working on his thesis on ski glide, he discovered that he could get very good results by steel scraping the skis instead of glide waxing them. His wife Antonina Ordina actually won the 30 km freestyle bronze medal in the 1995 Thunder Bay world championships on steel scraped skis: http://www.fis-ski.com/uk/604/610.html? ... raceid=659

Just to head off some of the protests:

The Kuzmin scrapers are actually structure tools. He sells three different versions that produce different structures. The plus scraper is fairly coarse, the universal scraper is fairly fine, and the cold scraper is almost smooth. I have all of them and I can confirm that they produce different results. The universal scraper produces skis that are good at -1 to -8 C but noticeably slow at -12 and +1. Skis scraped with the plus scraper hiss when they glide and are fast only on wet snow. Skis scraped with the cold scraper are very silent and fast at around -10 to -15, but are very slow at -2. But all the scrapers cut instead of grind, and this is important, because cutting creates a less fuzzy ski base microstructure compared to grinding.

Scraping isn't exactly the right word for what's happening, I think, the scrapers make a clean cut, even though the edge is trailing. They're thick, hard, completely rigid, and very sharp, totally unlike e.g. the Swix steel scraper.

There is no doubt that you can currently achieve better glide with stone ground skis and waxing, brushing and fluoro powders. The question is how much better. In my personal experience, Kuzmin vs glide waxing matters less than the choice of ski camber and pressure zones, kick wax and structure type, but Kuzmin scraping removes a lot of work and all the mess. Kuzmin scraping is much better than not waxing sufficiently often. I can't feel any difference compared to the Swix low-fluorine glide waxes + thorough brushing.

I think Kuzmin is right that wax is a poorer material for glide than the raw ski base and that cutting is inherently better than grinding. I believe the reason why Kuzmin scraping is not competitive at the WC level is that the number of different structures available with scraping is so limited, and that a whole lot of waxing and brushing will after a while also produce a very smooth ski base microstructure.

I think that unless you have multiple different pairs of skis exclusively for racing, you might as well switch to Kuzmin. I'll bet that a universal grind on slightly too wet or too cold snow is slower than the correct Kuzmin structure.

Brushing after scraping is really important. I use Kuzmin's angle grinder nylon brush, because it performs the equivalent of a half hour of brushing in about two minutes.

My personal experience is that I get a surprisingly good glide which lasts incredibly long. No dust or smoke and more than good enough for training. Right now I've skied about 250 to 300 km on my nanosonics since last prep, and they're still greasy black and I haven't been outglided even once this season. It's also extremely convenient to be able to switch to a different structure in half an hour instead of sending the skis away and paying for grinding, followed by great amounts of waxing and brushing to get the new grind ready.

I'm currently performing an experiment with my old skate skis, I've scraped one of them. So far it seems that the stone ground ski picks up wax and gunk from the track while the scraped one doesn't. This is just 20 km after gliding/scraping. Also, the scraped one does much better at the water drop test after skiing.

http://www.kuzmin.se/pgs/intr_engl.html
http://www.kuzmin.se/pgs/scrapers_engl.html

kuan
Ski Forum God
Posts: 1287
Joined: Fri Dec 01, 2006 9:28 am
Location: Golden Valley Minnesota
Contact:

Re: Kuzmin scraping and structure

Postby kuan » Wed Feb 20, 2013 4:11 pm

I suppose in nice clean snow and in blue extra temperatures it could work quite well.
Support http://www.mattliebsch.com

Pie. It just fills the cracks of the heart - Paul Blart

Cucicak
xcskiforum 20K
Posts: 34
Joined: Mon Dec 10, 2012 1:13 pm
Location: Moravia Region, CZ

Re: Kuzmin scraping and structure

Postby Cucicak » Wed Feb 20, 2013 4:56 pm

How does Kuzmin's technique tie up safety wise? Now that there is a lot of stuff on waxing being harmful to the lungs.
"newcomers should not be frightened by images of sweating figures struggling through the wilderness"

osloskier
xcskiforum 40K
Posts: 252
Joined: Tue Feb 05, 2013 2:28 pm
Location: Oslo, Norway

Re: Kuzmin scraping and structure

Postby osloskier » Wed Feb 20, 2013 5:01 pm

kuan: The dirtier the snow, the better scraping gets. The ski base seems to be too slick to pick up gunk. From what I hear, Kuzmin is almost competitive on ice and frozen, coarse grained snow.

Cucicak: No glide wax, no fumes. The scraper produces fluffy grey shavings that my vacuum cleaner is happy to devour. The ski base is made from polyethylene, which is harmless unless you set fire to it. You might want to wear gloves so you don't cut yourself. And you need to be careful with the rotational direction of the angle grinder brush - if it catches on the end of the ski you'll get a nasty surprise. It will probably not break the ski, but it will make a rather loud bang and your heart rate will be at about 190. Speaking from experience :shock: It should rotate rearwards, and you don't want to brush the upper part of the tip.
Last edited by osloskier on Wed Feb 20, 2013 6:51 pm, edited 1 time in total.

Cucicak
xcskiforum 20K
Posts: 34
Joined: Mon Dec 10, 2012 1:13 pm
Location: Moravia Region, CZ

Re: Kuzmin scraping and structure

Postby Cucicak » Wed Feb 20, 2013 5:33 pm

Interesting stuff, Im a bit of a hypochondriac over things like this, Im always battling with people in my neck of the woods over asbestos so was worried to hear about the wax but I see its ski wax technicians most at risk then the twice a month waxer. But with 300 klicks skied and still going strong it might be worth using as an alternative to waxing.
"newcomers should not be frightened by images of sweating figures struggling through the wilderness"

Raubie
xcskiforum 50K
Posts: 196
Joined: Mon Feb 09, 2009 1:13 pm
Location: Canada

Re: Kuzmin scraping and structure

Postby Raubie » Wed Feb 20, 2013 10:25 pm

I guess like most I've invested too much moola on waxing equipment just so I get a Christmas card from Swix HQ thanking me for my blind devotion. But you present it well, warts and all.

Do you know if any of the Swedish development teams have tested Kuzmin's 'system' alongside their traditional waxing regimen? I guess I'm thinking they'd be keen to use his system if it offered advantages in some conditions.

osloskier
xcskiforum 40K
Posts: 252
Joined: Tue Feb 05, 2013 2:28 pm
Location: Oslo, Norway

Re: Kuzmin scraping and structure

Postby osloskier » Thu Feb 21, 2013 6:08 pm

Raubie: You can always sell your waxing gear, you know ;)

But as I said, Kuzmin is not as good as top notch waxing, except possibly on ice and frozen coarse snow. If you pour sufficient amounts of work and/or money into it, grinding/waxing is better, so I can see why you might want to continue to wax your racing pairs. But for training and touring, I think Kuzmin is unbeatable due to near-zero maintenance and perfectly acceptable glide. Many people also choose to use scraped skis in Birken and Vasaloppet - but not the elite. Some people combine Kuzmin scraping and fluoro and report good results - but not top results.

I know for a fact that the Norwegian team has tested Kuzmin, I talked to one of the waxers about it. He was the one who said that it's actually really fast on ice and frozen coarse snow. He also said that combined with rilling, Kuzmin scraping can yield fairly good results. But for them to switch to Kuzmin, it would have to be faster in one or more types of snow, they can afford to pamper every ski pair to whatever extent is necessary and then some.

What I know for certain is this: I used to spend a lot of time glide waxing skis. Now I spend more time skiing instead, because I just grab my skis and go. And compared to the universal grinds and LF wax I used to use, I find that Kuzmin scraped skis glide better.

Loran
xcskiforum 20K
Posts: 78
Joined: Wed Apr 23, 2008 3:50 pm

Re: Kuzmin scraping and structure

Postby Loran » Fri Feb 22, 2013 4:14 pm

Thanks for the report.

I've be using Kuzmin scrappers for many years and then Hi-speed brushs and polishing for three seasons and then PTFE drum for two seasons. You can find my posts on that forum.

All three pass combined is giving matching glide to best fluoro "waxing" IMHO. Plus a much longer lasting...

(I'm not comparing it to "booster" which last only for a couple of km and act more like a lubricant.)

But keep in mind that it's the ski stiffness and the structure that does it almost all, depending on the conditions.
Assuming that your base is well polished ; Whatever the base prep, wrong skis will always have much higher friction that correct skis.

So, I know have 3 pairs of skis, Kuzmin prepped twice a year. I spend much more time skiing and less time in te basement. I just pick up the right skis and go.

Kuzmin is brilliant.

osloskier
xcskiforum 40K
Posts: 252
Joined: Tue Feb 05, 2013 2:28 pm
Location: Oslo, Norway

Re: Kuzmin scraping and structure

Postby osloskier » Fri Feb 22, 2013 5:16 pm

Loran wrote:I've be using Kuzmin scrappers for many years and then Hi-speed brushs and polishing for three seasons and then PTFE drum for two seasons. You can find my posts on that forum.


The PTFE drum tends to flatten the structure, doesn't it? Can you feel the difference, or do you need a stopwatch to measure the improvement? Have you tried the PTFE angle grinder brush yet?

All three pass combined is giving matching glide to best fluoro "waxing" IMHO. Plus a much longer lasting...

(I'm not comparing it to "booster" which last only for a couple of km and act more like a lubricant.)

But keep in mind that it's the ski stiffness and the structure that does it almost all, depending on the conditions.
Assuming that your base is well polished ; Whatever the base prep, wrong skis will always have much higher friction that correct skis.


Agree. But only three different structures are available with Kuzmin scraping, if you exclude rilling, that is. I wouldn't think that's enough for winning world cup races. For example, I think there's a gap between the plus and the universal scraper where none of them is optimal - moist, fine grained snow around 0 to +1.

So, I know have 3 pairs of skis, Kuzmin prepped twice a year. I spend much more time skiing and less time in te basement. I just pick up the right skis and go. Kuzmin is brilliant.


That's my plan too, but I don't have enough ski pairs yet. Currently I'm using my classic Nanosonics at -1 and colder so I can use relatively hard kick waxes or ice klister/wax combinations and the universal scraper. I switch to the cold structure whenever several days of -10 C or colder temperatures are forecast. But I'm looking for a pair for really cold conditions. If it's around 0, I'll take the skate skis, so I don't have to deal with soft kick waxes. I just got them, so they still have a universal stone grind, but I'll scrape them too. Don't know yet whether the plus or the uni scraper will be better for 0 C. I have two more ski pairs, but I only use those in conditions that might damage the two good pairs.

I still haven't heard a single Kuzmin report from the US or Canada, I think...

Loran
xcskiforum 20K
Posts: 78
Joined: Wed Apr 23, 2008 3:50 pm

Re: Kuzmin scraping and structure

Postby Loran » Sun Feb 24, 2013 3:18 pm

Yes the drum flattens the topography, for good, in most conditions. Using a manual rolling tool before the final polishing is always an option.

For wet condition, using a riller is the best way to achieve good glide. But you need to dedicate a pair for that because that kind of structure is hard to remove.

I don't have enough skis to be able to test different structures.

People who say that a riller unbroken structure attract dirt are misled by the fact that they are most probably using a soft wax at the same time.
The main problem with the drum is that is requires skill and training, to apply without burning the base.
Also, there are bases that have less cohesion that others. Then, bits of base are teared off the base. You have then to lower the rpm and clean the drum over a copper brush frequently.

I have not yet purchased the PTFE brush. I''m waiting for the forthcoming manual structure tool to group an order.

MN Hoser
Ski Forum God
Posts: 1069
Joined: Tue Dec 12, 2006 12:26 pm
Location: St. Paul, MN

Re: Kuzmin scraping and structure

Postby MN Hoser » Sun Feb 24, 2013 4:43 pm

The Kuzmin thing is intersting, but I had some doubts because he seems to push the idea that scraping was better than waxing in all conditions. When I started skiing, I didn't ever wax, so I got a fairly good idea that not waxing could be fairly fast.

In my mind, not waxing should be fastest in really dirty, warm conditions (like Thunder Bay). Wax picks up dirt and wax smooths structure. So a non-waxed ski in dirty warm seems like a perfect time to test.

In old snow or churned up ice is the time when waxing is easy. (You can wax with anything.) Finally, the PTFE roll sounds like a great idea. it would be interesting to experiement with.

Jay

osloskier
xcskiforum 40K
Posts: 252
Joined: Tue Feb 05, 2013 2:28 pm
Location: Oslo, Norway

Re: Kuzmin scraping and structure

Postby osloskier » Sun Feb 24, 2013 5:53 pm

Loran wrote:Yes the drum flattens the topography, for good, in most conditions. Using a manual rolling tool before the final polishing is always an option.

For wet condition, using a riller is the best way to achieve good glide. But you need to dedicate a pair for that because that kind of structure is hard to remove.

I don't have enough skis to be able to test different structures.

People who say that a riller unbroken structure attract dirt are misled by the fact that they are most probably using a soft wax at the same time.
The main problem with the drum is that is requires skill and training, to apply without burning the base.
Also, there are bases that have less cohesion that others. Then, bits of base are teared off the base. You have then to lower the rpm and clean the drum over a copper brush frequently.

I have not yet purchased the PTFE brush. I''m waiting for the forthcoming manual structure tool to group an order.


Thanks for the info, very interested in hearing how the PTFE brush works when you get it.

I have a Red Creek riller, and I find that the structure it leaves is easy to remove by either gliding the skis in the standard way or by re-scraping them. But I got that tool just for fun, and I haven't really learned when to use it or how hard to press in various conditions yet.

Some perspective on the magnitude of the differences between Kuzmin scraping and waxing: Today I assumed the snow would be moist, as yesterday we had a few cm of fresh, wet snow and +2 C. I waxed the nanosonic skates to get rid of klister and dirt from yesterday, as I still haven't scraped them. If they were scraped I would have just wiped the gunk off with base cleaner, of course. I also added a 1 mm straight rilled structure as an experiment. Then it turned out the snow that was so wet yesterday had turned into fine, dry powder overnight, and in the forest, shielded from the sun, it had somehow survived +2 C during the day. My, oh my those skis were bone dry, they would not move unless I kept pushing. In the downhill where my GPS logged 52 km/h yesterday, I only managed 47 today, even though I was crouching down much more to gain some speed. But while DP'ing across a lake, where the sun had baked the snow all day, I had great glide. I think getting the structure right is much more important than what wax, if any, you put on top of it. The difference between rilled/not rilled was enormous compared to the difference (if any) between universal stone grind + Swix LF vs Kuzmin U + rotobrushing.

Loran
xcskiforum 20K
Posts: 78
Joined: Wed Apr 23, 2008 3:50 pm

Re: Kuzmin scraping and structure

Postby Loran » Mon Feb 25, 2013 11:51 am

MN Hoser wrote:The Kuzmin thing is intersting, but I had some doubts because he seems to push the idea that scraping was better than waxing in all conditions.

From what I read from his Ph D thesis : According to his own research and what had been done before, it seems that science never came out with any reason for adjusting the hardness of the gliding surface. The base has to be as hard as possible and as hydrophobic as possible. That's it.

Super-hydrophobic would not necessary be better because of increased friction of the topography / texture.

What's left to adjust is the pressure (stiffness) and the structure.

Apparently the wax industry moved the complexity of kick waxing (which is indeed complex) to glide waxing without any serious backing science.

Together with my friends we have a fleet of 6 Kuzmin prepped pairs having different stiffness and structures.
It's good to experiment the (huge) differences in glide knowing that there's absolutely no interference by the wax.

SpecialGreen
xcskiforum 20K
Posts: 83
Joined: Fri Jan 04, 2013 3:42 pm

Re: Kuzmin scraping and structure

Postby SpecialGreen » Mon Feb 25, 2013 8:31 pm

Loran wrote:t seems that science never came out with any reason for adjusting the hardness of the gliding surface. The base has to be as hard as possible and as hydrophobic as possible. That's it.


I imagined that the glide wax had to create enough friction to make a very thin layer of water, similar to the way an ice-skate melts the ice and leaves a trail of water behind it. Ice+water-on-top = very slippery. Too much friction, and you stick; not enough and you grind.

But that could be all wrong.

Loran
xcskiforum 20K
Posts: 78
Joined: Wed Apr 23, 2008 3:50 pm

Re: Kuzmin scraping and structure

Postby Loran » Fri Mar 29, 2013 12:51 pm

SpecialGreen wrote:I imagined that the glide wax had to create enough friction to make a very thin layer of water, similar to the way an ice-skate melts the ice and leaves a trail of water behind it. Ice+water-on-top = very slippery. Too much friction, and you stick; not enough and you grind.
But that could be all wrong.


To create a thin layer of water by breaking snow crystals, the surface has to be harder than crystals. Similar hardness has never been proved to be better at that job.
So, to cope with very cold snow, the harder the better.
Note that below -15°c, snow crystals are harder than the UHMWPE ski base (which is itself much harder than any wax)

Maintaining the optimal thickness of the water layer is the job of the structure/topography + ski stiffness.
Then, the most hydrophobic possible base prevents water adhesion.
That's why ski bases are made of UHWMPE (very hard and very hydrophobic) and not from another "spongious" or "waxophil" material. If they could be made of PTFE or cross-linked PTFE that would even be better. No doubt that sooner or latter they will, because huge progress have been made in glueing.
The only drawback is that PTFE is slightly heavier.


Return to “Wax and Waxing”

Who is online

Users browsing this forum: No registered users and 1 guest