Power Kite Forum - Melting ski bases

Melting ski bases

Prussik - 6-11-2013 at 09:29 AM

Over the years there have been rumours every now and then of ski bases melting when used on ice at speed. I haven’t experienced this myself and have been rather sceptical of this anecdotal evidence. After all it is hard to think of better cooling than contact with ice.

Yesterday, after a couple of hours on ice I noticed an increased drag when going over small drifts. I stopped and looked at the bases of my iceskis. Strips of p-tex next to the edge peeled off and broke off. That would not be so odd, however there are areas of p-tex melting, flowing and firming up in the new distorted positions. The ice conditions were very good, easy grip, curling type. The wind was gusty and strong – I was on 1.5 reduced to 1.2 that needed some flying in the lulls. Speeds were under 50 km/h. Because of limited space there was a lot of gybing which can be hard on the edges. It was warm, around freezing. The most affected ski is the one edged harder due to wind direction. Nothing like this ever happened in faster cruising.

B-Roc - 6-11-2013 at 10:02 AM

where are you that there is already ice safe to ski on?

erratic winds - 6-11-2013 at 10:26 AM

I don't know but I would imagine Feyd is the expert on this!

doneski - 6-11-2013 at 02:11 PM

I know it happens but sounds like an urban legend.
Im going to test this by rubbing an ice cube really fast on a knife until I make fire.

B-Roc - 6-11-2013 at 03:21 PM

Quote: Originally posted by doneski

.
Im going to test this by rubbing an ice cube really fast on a knife until I make fire.

rectifier - 6-11-2013 at 06:32 PM

Yeah, really, where is the ice! And flying a 1.2m, you are fast enough to melt your base!? Are you flying in a hurricane in the NWT?

I think we have about 1/2" of ice here on the smallest sloughs. And it's been bloody cold.

I'm surprised by this because I used to ride the iciest slopes when I snowboarded the coastal mountains in BC. I experienced some nasty wear on the base near the bindings, but never any melting!

BEC - 6-11-2013 at 06:45 PM

I want some of whatever you are doing ..... :crazy:

canuck - 6-11-2013 at 10:48 PM

Prussik is out of Calgary. He is always the first out and kites well into May :thumbup:

The Red Deer area has been cold enough at night to freeze sloughs or shallow lakes but he usually starts his season at Lac des Arcs near Canmore.

It would take temperatures of 125-140C to melt P-tex so I think you would leave a trail of steam if you were actually melting the ski base. It will be interesting to hear more.

Kamikuza - 7-11-2013 at 04:51 AM

I know someone who'll know...

skimtwashington - 7-11-2013 at 07:53 AM

All sounds strange. I think there can be some chemical breakdown with age in plastics and materials that can cause brittlness and causes breaking off...... but this melting/flow seems improbable. But your experience says more perhps.

Any pics of base?

maybe a hallucination?....someone's brain is melting from smoking 'ice'...?

erratic winds - 7-11-2013 at 08:51 AM

Quote: Originally posted by doneski

I know it happens but sounds like an urban legend.
Im going to test this by rubbing an ice cube really fast on a knife until I make fire.

Quote: Originally posted by BEC

I want some of whatever you are doing ..... :crazy:

Quote: Originally posted by skimtwashington

maybe a hallucination?....someone's brain is melting from smoking 'ice'...?

Can't tell if you're joking or if every one of you got out of bed on the wrong side that day, kinda rude comments.

PrairieWind - 7-11-2013 at 08:58 AM

Driving from banff eastward on Sunday I could see that Lac des Arcs was going to be ready in a day or two. Prussik was on the ice at Lac des Arcs last year in October.

My guess is that the age of the skis (serious number of miles done) and the modification made to the skis for caused the degradation. The serious number of miles that he has done with those skis would be difficult to imagine. He has well over 100 days on the ice and snow each year, well over, but uses different skis and various other ice toys depending on conditions.

rectifier - 7-11-2013 at 08:31 PM

Yeah, Lac des Arcs does explain some things :cool:

Cold and tons of wind, and I seem to recall hearing tales of a kiter who flies small kites on long lines on Lac des Arcs in the crazy winds so that explains the 1.2m thing.

A shame that it's a bit far from my place.
I'm going up to Red Deer to do a job next week maybe I can get a little riding in if things are freezing there :eureka:

I guess alpine skis are not really meant for long distance travel - they probably travel more in a day of kiteskiing than in 10 on the hill - and they don't get waxed at lunch time! Hard on the bases for sure, never thought of it that way

Feyd - 8-11-2013 at 06:20 AM

Not all skis are created equal. Some last longer than others and but most can last a long time on the hardest ice if certain techniques are employed.

"Base melt" is not a myth. I've had 2 pairs of my own skis do it and I know of a couple others. Base material is plastic and it comes in various types, extruded (really old school and some modern kids skis) and modern Ptex are the most common. Ptex is more durable but both have a certain elasticity and can be torn, bent and stretched. Heat makes the both plastics more pliable. Skis rely on heat to glide. The friction that a ski generates on the surface melts the snow/ice and creates a water layer. That is what you are gliding on not the snow. Wax and base structure are used to manage how the water behaves on your bases. If you don't have wax or a structure on your base or the wrong combination, you don't go too well.

What I'm pretty sure happens with base melt is a small chain of events. Intitially the base has to become slightly delamed from the ski. At the edge. This could be triggered but heavy edging on ice without feathering, over heating when waxing or both. The separation is small, pretty much inpossible to detect and doesn't become apparent util you've ridden on it for a while.

The next thing that happens is the separation opens up, ever so slightly, and allows ice or snow to be packed in with each turn. This sets things in motion for more separation as you pack more ice in. this progresses to a point where the base has pulled away enough to provide a high spot. As you cruise around it causes more, localizes friction on the base, the base softens, pulls away more, more snow goes in, base gets separated more, bigger high spot, more friction, rinse and repeat.

Eventually you have a base that is being subjected to high heat, friction and in one direction. The end result is a base delam with a wierd sort of ribbon look to it with a few tears here and there and maybe some lost ptex. The ski beneath the base where it's pulled away is completely exposed usually. The damage has a very fluid look to it. You usually realize there's a problem when you go to edge and it feels like you're on ball bearings.

The best repair options are (depending on size) a base weld with a Ptex welder, no drip candle nonsense, or an inlay.

On an average day here we put between 40-70miles in. Most of us have get about 2-4 seasons out of a ski on hard ice. Unlimited on deep snow. The ski area in front of my house is 1 mile top to bottom. Last season I got 1200 miles in, most at speed,lost one pair of skis.

To base melt actually.:D

Debating if I should fix it. Not much edge left.

Prussik - 8-11-2013 at 08:47 AM

Responding to a few (very few) individuals capable of rational discussion and ignoring the rest of mindless sarcasm and hostility - let me refer to the first paragraph of the first post and make it quite clear that I would be much more comfortable with a more plausible explanation if I could find one. This would require the knowledge of how to make p-tex blister and dislocate to create elevated ripples without applying heat. And that’s what is in evidence. And we know how tough this stuff is. The other thing that bothered me was the fact that nothing like that has ever occurred on faster and longer reaches. For that I found an explanation which boils down to the fact that in those conditions I never use iceskis but skates. I overestimated the size and depth of drifts in the distance.

No matter what there is no danger of “smoking across the lake” becoming anything more than just a figurative speech. At 50 km/h the ice is in contact with the “hot” part of the iceski for about 15 milliseconds. This is not long enough to turn ice into vapour even at temperature much higher than what is needed to melt p-tex.

Feyd - 8-11-2013 at 11:02 AM

Maybe I should be more clear. We're not talking in terms where the base is heated to the point of going to a liquid state.

Simply softer than when it is firmly epoxied to the ski core and edge material. Especially if the base material has been tuned a lot and is running thin. The deformity is more an action of force than an action of actual "Melt" and is probably more prone to the circumstances induced by minor base delam than high speeds.

Tearing Ptex leaves a ripple effect not unlike what you see in a leaf of kale. That's right I used kale and Ptex in the same sentence. FIrst ever I bet. :D

BEC - 8-11-2013 at 12:24 PM

Just for the record...I thought that we were still allowed to joke around on the forum...I think waking up on the wrong side of bed would be taking these three quotes from 3 PKF members to heart and not realizing that there was some joking around about the subject. I mean after countless posts of helping people, talking about safety, donating time and money to our sport etc., etc., that this would be taken so seriously. Really?

Quote: Originally posted by erratic winds

Quote: Originally posted by doneski

I know it happens but sounds like an urban legend.
Im going to test this by rubbing an ice cube really fast on a knife until I make fire.

Quote: Originally posted by BEC

I want some of whatever you are doing ..... :crazy:

Quote: Originally posted by skimtwashington

maybe a hallucination?....someone's brain is melting from smoking 'ice'...?

Can't tell if you're joking or if every one of you got out of bed on the wrong side that day, kinda rude comments.

erratic winds - 8-11-2013 at 01:02 PM

Based on the response from the original poster, Prussik, I wasn't the only one who felt those comments strayed a fair bit from humorous.

PrairieWind - 8-11-2013 at 05:55 PM

I was also one of those that thought that some of the comments strayed a fair bit from humorous.

I live a wee bit south and east of Prussik but am going to check my first ice of the year tomorrow. I hope it does not snow so that I get some nice black ice for the first go round. If all goes well I will just have to sharpen my skates and not check my bases for the melt!

Cheers from the great white north.

rectifier - 8-11-2013 at 09:25 PM

Hmm, from this description it sounds like this may have been the cause of the unusual wear on my "coastal ice board" which is now my slush board. It took the form of missing ptex right behind the edge on my toe edge, near and between bindings. I use my toe edge a lot heavier in really icy riding as it has more grip.
I always put it down to abrasion from fine ice particles kicked up while edging at high speeds. But this mechanism sounds plausible as well, and conditions there were very warm.
Have never experienced it on the prairies or while kiting.

Agree that sarcastic comments to discussion ratio was pretty poor. Perhaps BEC genuinely wanted some of what you were doing though... high speed early season ice riding :D

skimtwashington - 8-11-2013 at 09:45 PM

I was joking and did imply or defer to personal experience trumping the improbability(as more than anectdotal)...before I launched into my ribbing.

When something unexpected, or thought to be unlikely actually happens... human response is commonly to say ,"really..?."

Sometimes it is JUST as common to make a joke.

Leading in with a post on one's original skepticism of such an occurrence....
This just leads to a response where there's a choice of complete seriousness , a joke or a bit of both. The joke is about a rumor or legend turning out to be true... and joking that we don't believe you . It's not that we don't ACTUALLY believe you....

Nothing the three of us said was unusual...... and more so... no one said anything to be taken SERIOUSLY (.Did you notice my winking smile icon?) None of us meant to be rude...you should know. These were jokes-not 'mindless sarcasm'.

"Hostility"? No idea why you would feel hostility..

I am ALWAYS sorry if I make a joke that truly offended someone.

Frankly I wish there was more humor. Even if the attempt fails sometimes. If every discussion involves simply exacting measurements of information.. it would be smile-less and a shame.

Anyway...back to subject:

Feyd's final explanation sounds like an accurate one.

Feyd - 9-11-2013 at 05:24 AM

Rectifier, correct, you are losing base material at the edges.

This is common for anything that has been ridden for a long time, soft snow or hard, without flatting the base and occasional flat filing of the base and base edge. Crystals, especially in fresh cold snow are uber abrasive. Late season warm snow less so but ice, always. Skis and board that get to that point on the slope can be a nightmare of hooky riding but on the kite tend to ride pretty well. But that lippy inner edge becomes prone to blow out.

We base harden with some flavor of extreme old wax. Hot box it so that the base sint absorbes as much as possible then apply the flavor of the day. Slows down the base loss and on slope protects from core shots. :D

snowspider - 12-11-2013 at 07:23 AM

Irregular pounding and pressure rolling along that narrow contact surface could be causing the softer plastic to wavelike creep over the harder subsurface its bonded to. Additionaly any tiny delamination will cause even greater deformity to occure and setup areas that are free to break off. Add to that any freeze thaw cycle going on and VOILA` thrashed and trashed said ski.