Post Ski Stone Grind Base Cleaning

[Dakine]

Toni,
That's a load of good information.
I had always assumed the typical drawing of a sintered ski base that shows open porosity is correct.
Now you have me wondering.

The Celanese product brochure of GUR UHMWPE is not clear on ski base manufacture.
https://www.celanese.com/-/media/En...es/GUR-015-UHMW-PE-Overview-PM-EN-r1-0916.pdf
Porous sintered UHMWPE is used for all kinds of filters.
Pressure sintering or compression molding the material to near 100% density to make things like the meniscus I my knee replacement is common.
You are the first person who has suggested that sintered ski base material has no porosity.
Dr Geissbuehler's patents don't say anything about density, they are about interesting additives.
Looks like I have some homework to do.
I do know that when the sintered logs are peeled into strips, some areas of the log make better bases that others.
I have also heard that some pieces of base material run so well they are peeled off and reused on new skis.
You know anything about that..?|

 

[Jacques]

As the late Doug Coombs said in his Q and P tune......"Citrus, environmentally safe....you can drink it...you can put it on your salad"......lol

Yea, that's a funny old video.
It goes to show some take their skis too seriously!
I am serious, but I keep it in reason as someone that skis for fun. If I did not have fun messing with skis, I would be missing half the fun. I enjoy that part.
Some can have fun on a 2 x 4 and that okay too.

I have been very happy with the Glide Wax Cleaner and will continue with it and a bit of quality ventilation.

 

[Seldomski]

Good thread here about ski base material and how it works:

https://www.pugski.com/threads/myths-about-uhmw-base-material-and-new-base-material-idea.2460/

 

[Swiss Toni]

I guess that most people probably think sintering produces products like this sintered bronze filter, which is produced using pressureless sintering.

If pressure were also to be applied during the sintering process you would likely end up with a solid bronze disk.

Transmission electron microscopy, can magnify UHMWPE by up to 16.000 times. An ultramicrotomed slice of the polymer is typically stained with uranyl acetate to improve contrast. The staining makes the amorphous regions turn grey and the crystals appear as thin ribbon-like lamellae.

When polythene bases first came onto the market, they were much slippier than the bases they replaced so I guess the wax manufactures had to dream up some reasons to get people to continue using it in order to stay in business, pores would have sounded pretty good to someone who associated sintering with the product above.

 

[Jacques]

@Swiss Toni, so do you wax your skis, or are you strictly a steel scraper guy?

I guess if one only steel scrapes, then they would have no use for Swix Glide Wax Cleaner or any other wax removers at all.

Funny though that the few top makers of base material actually claim some wax absorption even in their extruded bases.

Would a couple mg's of wax in a square cm make any difference?

BTW nice photo above. Looks just like a piece of paper. It's fibers.
My understanding is wax goes in between those fibers,

 

[Swiss Toni]

Jacques, I wax my skis, I don’t use a metal scraper. I just try to tune my skis as efficiently and as effectively as I can.

My procedure is to periodically get the bases ground and the edge angles set at a local shop that I trust to do as I ask. After grinding the bases are wiped with technical grade D-limonene (citrus solvent) and are then waxed using an infrared waxing machine, we gave up using hot boxes about 10 years ago. Polyethylene readily absorbs infrared radiation and infrared heating is widely used in industry to heat plastic sheet for thermoforming. As long as you don’t want it motor driven, they are quite easy to build (waxing starts at 2:20).


In between grinds I infrared wax, scrape (they don’t need much scraping) and brush them with a bronze brush. When the edges need sharpening, I use an edge grinder that rolls along the base of the ski. I use odorless mineral spirits for all cleaning between grinds.

The figures for wax absorption given by the manufactures are based on lab tests, they soak samples of base material in wax at 110°C. The wax penetrates from both sides, we only have access to one side so the amount we can get into the base is likely to be half the quoted amount at best assuming you can achieve the same temperature.

The photo does looks similar to a photo of some non-woven fabric, but it’s very highly magnified if you look closely there is a scale in the bottom left hand corner. In the amorphous regions the molecules are all jumbled up like spaghetti and in the crystalline regions the are neatly folded.

 

[Jacques]

Jacques, I wax my skis, I don’t use a metal scraper. I just try to tune my skis as efficiently and as effectively as I can.

My procedure is to periodically get the bases ground and the edge angles set at a local shop that I trust to do as I ask. After grinding the bases are wiped with technical grade D-limonene (citrus solvent) and are then waxed using an infrared waxing machine, we gave up using hot boxes about 10 years ago. Polyethylene readily absorbs infrared radiation and infrared heating is widely used in industry to heat plastic sheet for thermoforming. As long as you don’t want it motor driven, they are quite easy to build (waxing starts at 2:20).


In between grinds I infrared wax, scrape (they don’t need much scraping) and brush them with a bronze brush. When the edges need sharpening, I use an edge grinder that rolls along the base of the ski. I use odorless mineral spirits for all cleaning between grinds.

The figures for wax absorption given by the manufactures are based on lab tests, they soak samples of base material in wax at 110°C. The wax penetrates from both sides, we only have access to one side so the amount we can get into the base is likely to be half the quoted amount at best assuming you can achieve the same temperature.

The photo does looks similar to a photo of some non-woven fabric, but it’s very highly magnified if you look closely there is a scale in the bottom left hand corner. In the amorphous regions the molecules are all jumbled up like spaghetti and in the crystalline regions the are neatly folded.

Citrus and mineral spirits. So you do do some cleaning and waxing as well.
Nice. Thanks for getting back on the questions.
For a while I was thinking you were the Kuzmin guy!
I know not much was is absorbed into the base, yet it seems to me every mg makes for better glide. Not waxing over dirt and "junk" seems to help as well.
These threads do drift around, and that's to be expected as usual. Thanks for sharing your base cleaning methods.
As for the infrared.......well, I'm still not sold on that. I'm sure it works, but not sure if it's better than hot boxing and iron waxing with several cooling and heating cycles.
I do like those infrared machines way better than someone using an iron on the skis in a commercial shop. It only takes one iron mistake to ruin a base.
Oh BTW, is that your shop in the video?

 

[Shawn C.]

Jacques, I wax my skis, I don’t use a metal scraper. I just try to tune my skis as efficiently and as effectively as I can.

My procedure is to periodically get the bases ground and the edge angles set at a local shop that I trust to do as I ask. After grinding the bases are wiped with technical grade D-limonene (citrus solvent) and are then waxed using an infrared waxing machine, we gave up using hot boxes about 10 years ago. Polyethylene readily absorbs infrared radiation and infrared heating is widely used in industry to heat plastic sheet for thermoforming. As long as you don’t want it motor driven, they are quite easy to build (waxing starts at 2:20).


In between grinds I infrared wax, scrape (they don’t need much scraping) and brush them with a bronze brush. When the edges need sharpening, I use an edge grinder that rolls along the base of the ski. I use odorless mineral spirits for all cleaning between grinds.

The figures for wax absorption given by the manufactures are based on lab tests, they soak samples of base material in wax at 110°C. The wax penetrates from both sides, we only have access to one side so the amount we can get into the base is likely to be half the quoted amount at best assuming you can achieve the same temperature.

The photo does looks similar to a photo of some non-woven fabric, but it’s very highly magnified if you look closely there is a scale in the bottom left hand corner. In the amorphous regions the molecules are all jumbled up like spaghetti and in the crystalline regions the are neatly folded.

Willi's? As in Pittsburgh area Willi's?

 

[Swiss Toni]

Jacques, I live in Switzerland hence the alias Swiss Toni and the picture of the Matterhorn so I am unlikely to own a shop in the in Pittsburgh area. Infrared waxing is a Swiss innovation the guy who came up with the idea got Toko to do a lot of the testing. This is one is located at their R&D center.

The goal is to make the bases harder and more hydrophobic so that they glide better, you can’t do that by hot boxing because the temperature is too low. Waxing irons need a layer of wax to glide along, most of which you have to scrape off and throw away, the cheaper irons such as your TOKO T8 have large temperature fluctuations, ± 10°C in the case of the T8, the temperature of a decent iron such as the Swix T71 Alpine World Cup only fluctuates by only ± 2°C. The components I used to build my IR waxer cost a lot less than a decent iron and I use a lot less wax.

 

[cantunamunch]

Willi's? As in Pittsburgh area Willi's?

Yes, that Willi's.

 

[Jacques]

Jacques, I live in Switzerland hence the alias Swiss Toni and the picture of the Matterhorn so I am unlikely to own a shop in the in Pittsburgh area. Infrared waxing is a Swiss innovation the guy who came up with the idea got Toko to do a lot of the testing. This is one is located at their R&D center.

The goal is to make the bases harder and more hydrophobic so that they glide better, you can’t do that by hot boxing because the temperature is too low. Waxing irons need a layer of wax to glide along, most of which you have to scrape off and throw away, the cheaper irons such as your TOKO T8 have large temperature fluctuations, ± 10°C in the case of the T8, the temperature of a decent iron such as the Swix T71 Alpine World Cup only fluctuates by only ± 2°C. The components I used to build my IR waxer cost a lot less than a decent iron and I use a lot less wax.

Yea, okay, I get it. You don't like my T-8 or my hot box! I do use infrared elements in my box, but it's just for heat! Can't pass over skis!
But really, I don't see that much fluctuation with my T-8. I'd say maybe 5 to 7 degrees F. 10C is a lot!

 

[Dakine]

Now that I know we are dealing with fully dense polymer, I have new questions.
The amount of crystallinity in UHMWPE is influenced by many factors, most notably how quickly it is cooled from the crystalline melt point.
Quick cooling increases the fraction of amorphous polymer while slow cooling and annealing allows for the development of maximum amounts of crystalline polymer.
When UHMWPE powder is compression molded into a log that is later peeled into base stock, the polymer on the outside of the log cools much faster than that on the inside.
The polymer that comes off the log near the center will have more crystallinity than that peeled from the outside.
The polymer from the outside of the log will absorb more wax than the stuff that is more crystalline from the inside.
The race ski manufacturers must know how much crystallinity is best and how to make bases with this amount.
We all know not all sintered bases are the same and some a much faster than others.
Now maybe we know why.


Another important factor in polymer mechanical properties is orientation.
When plastic is stretched, the molecules orient and this affects the properties.
UHMWPE strands are made incredibly strong by stretching during processing.
I wonder if ski base material is stretched to orient the chains along the direction of travel?

 

[Dakine]

I have always liked the concept of traveling infrared wax heaters because you can get the moving puddle hot without heating the bulk of the ski.
The UHMWPE will take much higher temperatures than the epoxy bonds that hold the ski together.
A hot puddle of wax heated by IR that only warms the surface has theoretical advantages.
Irons are crude and old tech but if used skillfully can make a moving puddle of hot wax without overheating the ski just like a traveling IR machine.

 

[Swiss Toni]

The crystallinity of most ski bases is around 50-55%. In the mid-1990s Isosport developed a process that they call “Controlled Crystallinity” to reduce the degree of crystallinity, it involves heating the skived film up to 140°C and cooling it between 2 steel rollers, by doing this they are able to get the crystallinity down to around 40%.

Rather than logs the manufactures make washer like disks that are around 140mm thick, there is no evidence that the crystallinity varies appreciably from the outside to the inside of the disks.

They don’t stretch it, after skiving one side is sanded and flame oxidized to enable it to be stuck to the rest of the ski.

Many people do get good results using an iron. A digital one with a thickish sole plate does a better job than one of the cheap ones with an adjustable bimetal thermostat, but at least 90% of the wax applied is wasted.

 

[Dakine]

Good stuff.
Quenching the hot polymer would result in minimum crystallinity for the grade used.
Flame oxidizing or plasma treating would be routine polymer processing tech.
But, I'm still trying to get a clue as to why some sintered bases are better than others......
If it isn't porosity, and it isn't crystallinity and it isn't orientation...what is it?
Marketing..?
Or could different molecular weight grades of UHMWPE be used for the best bases?
A higher MW base would be harder and more expensive to process.
Fun conversation.

 

[Jacques]

The crystallinity of most ski bases is around 50-55%. In the mid-1990s Isosport developed a process that they call “Controlled Crystallinity” to reduce the degree of crystallinity, it involves heating the skived film up to 140°C and cooling it between 2 steel rollers, by doing this they are able to get the crystallinity down to around 40%.

Rather than logs the manufactures make washer like disks that are around 140mm thick, there is no evidence that the crystallinity varies appreciably from the outside to the inside of the disks.

They don’t stretch it, after skiving one side is sanded and flame oxidized to enable it to be stuck to the rest of the ski.

Many people do get good results using an iron. A digital one with a thickish sole plate does a better job than one of the cheap ones with an adjustable bimetal thermostat, but at least 90% of the wax applied is wasted.

Ah, but that 10%! I use very little wax for a re-wax after base prep. Then again I don't ever run my iron over say 220 F for the hardest waxes I use.
Isosport is the stuff.

 

[Jacques]

Good stuff.
Quenching the hot polymer would result in minimum crystallinity for the grade used.
Flame oxidizing or plasma treating would be routine polymer processing tech.
But, I'm still trying to get a clue as to why some sintered bases are better than others......
If it isn't porosity, and it isn't crystallinity and it isn't orientation...what is it?
Marketing..?
Or could different molecular weight grades of UHMWPE be used for the best bases?
A higher MW base would be harder and more expensive to process.
Fun conversation.

I have heard say, that the techs don't even know why, but in testing some seem to go faster than others. Luck of the draw!

 

[Swiss Toni]

There are many different grades of base material and all sorts of additives the racing bases have higher molecular weights and more additives than the basic consumer bases. Take a look at the Isospeed product portfolio https://www.isosport.com/en/categories/isospeed I don’t know if they are still made, but there used to be double sintered ski bases, after sintering they would grind the disks up and re-sinter the resulting powder. The ski manufacturers also have their own formulations, Head has a patent for a base with Graphene / Graphene oxide additives. The possibilities are almost endless.

In general, the harder and hydrophobic the base is the faster the ski, but there are other things involved. Ski construction plays a big part, there are always slight variations and some skis are simply faster than others, which is why the manufactures employ testing teams to find out which skis are the fastest. When waxing its generally recommended to use a harder rather than a softer wax, hard wax is also more hydrophobic than soft wax. Over the last few years many waxes have been reformulated to make them a bit harder.

 

[SpauldingSmails]

If you had a ski stone ground, it should be cleaned well before you start base wax preparation.
This is long as always, but the theory and argument will be in the discussion, so listen to the entire thing before you give your take on the process.
It will be helpful if you can leave a video time in relation to your argument or comment such as at 13:50 etc.
Any information you have to add is always appreciated.
We all want to learn new stuff. (Me too!)
So please chime in with your questions or knowledge.
This is the link to the long video of my process.

Dude, I love your videos. I have an idea maybe you have entertained yourself. Instead of a stone grind, Imagine if there was a jig that held to a ski and could move up and down the length of the ski that could guide a brush diagonally across the ski. It would look like two foot long pieces of wood that were snug to the sides of the ski with two more pieces of wood fastened diagonally across those two over the base of the ski. A square wooden brush could fit just snug between the two diagonal pieces and slide back and forth. I have no pic, this is just an idea I had. Can a brush structure applied by such a jig do the same job as a stone grinder? Instead of putting in stone ground structure it would be a steel brush or brass brush created structure (pressure and material may vary as well as angle of brushing across the ski). In this case hopefully the removal of any base can be avoided, other than a light scraping if necessary.
What do you think of that?

 

[cantunamunch]

Dude, I love your videos. I have an idea maybe you have entertained yourself. Instead of a stone grind, Imagine if there was a jig that held to a ski and could move up and down the length of the ski that could guide a brush diagonally across the ski. It would look like two foot long pieces of wood that were snug to the sides of the ski with two more pieces of wood fastened diagonally across those two over the base of the ski. A square wooden brush could fit just snug between the two diagonal pieces and slide back and forth. I have no pic, this is just an idea I had. Can a brush structure applied by such a jig do the same job as a stone grinder? Instead of putting in stone ground structure it would be a steel brush or brass brush created structure (pressure and material may vary as well as angle of brushing across the ski). In this case hopefully the removal of any base can be avoided, other than a light scraping if necessary.
What do you think of that?

Or just use a steel rotobrush in a drill?