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The myth of ski wax??? - Page 10

post #271 of 286

Nope

post #272 of 286
Quote:
Originally Posted by Racer View Post
 

Nope


Ha ha. You mean bump!  You bored now that the Northern side of the globe is pretty much done for the season.  ;)

post #273 of 286
Quote:
Originally Posted by mdf View Post
 

Amorphous and crystalline regions are both sold, but differ on the atomic scale.  The disorganized arrangement lets compatible molecules sneak in:

 

From http://www.majordifferences.com/2013/02/difference-between-crystalline-and.html#.VxUfwfkrK_4

 

The heat helps because on the molecular scale it is manifested as jiggling atoms, helping wax wiggle in.  The atomic spacing gets larger, also, which helps too.

No way is wax passing through the interstitial atomic spacing due to thermal-induced vibrations. The amorphous v. crystalline effect is on a macrostructural scale not atomic. Whether the material is amorphous v. crystalline contributes to the macroscopic properties that in turn effect wax absorption. 

 

Base burn is a surface effect resulting from the ptex reacting with oxygen under conditions of extreme friction-induced localized heat and the accompanying increase in pressure. A waxed base will protect the base surface from this effect by serving both as a barrier layer and a mechanism to dissipate heat.

post #274 of 286
@Doctor DWould you please clarify whether you understand the amorphous domains to actually adsorb wax or not. I cannot tell from your post.
post #275 of 286

The microscopic voids in the base material absorb the wax; wax is not absorbed into the actual molecular structure of the base material. Like a sponge takes up water without the water penetrating the actual sponge material. Thanks for asking.

post #276 of 286

What evidence is the for such voids? And to the extent these exist, is there any evidence that they form an "open cell" vs a "closed cell" structure? Sintered base material is made under significant pressure...hence the "high density" bit...

post #277 of 286

Simply put, it's a fact that wax gets absorbed and it has to go somewhere & it isn't diffusing through atomic spacing. I have a PhD in chemistry and honestly it is common sense if you know polymer chemistry and have a feel for molecular diffusion. I don't need (and have no time to) write a manuscript on it and you're welcome to your own ideas, but that is what happens. I was tired of seeing this thread and thought I would put it to bed, but I guess not. It's all yours, enjoy, I have to build a new website (launching soon BTW with a big sale). Back to work....

post #278 of 286

Last word. I was a bit too loose with the sponge analogy. It was to push the concept of how wax goes into the base. I didn't mean to imply that the base was spongelike throughout the depth profile of the base. In fact, the wax is only able to penetrate a very short distance.  

post #279 of 286
Quote:
Originally Posted by Doctor D View Post

Last word. I was a bit too loose with the sponge analogy. It was to push the concept of how wax goes into the base. I didn't mean to imply that the base was spongelike throughout the depth profile of the base. In fact, the wax is only able to penetrate a very short distance.  

So the molecular properties of P-Tex change with depth?
post #280 of 286

Nope.

 

Let's try Swiss cheese.  You can have a surface that has holes/voids exposed but they only go so deep. There are lots more voids deeper into the cheese but the wax can't access them. So taking another slice of the surface (as in a fresh base grind of your ski) cuts off what you see but exposes new holes on the freshly-made new surface.

post #281 of 286
Quote:
Originally Posted by Doctor D View Post

The microscopic voids in the base material absorb the wax; wax is not absorbed into the actual molecular structure of the base material. Like a sponge takes up water without the water penetrating the actual sponge material. Thanks for asking.

Well I'm a PhD organic chemist myself and sponges made from cellulose do adsorb water into their molecular structure as well as into the voids or pores that we more commonly experience in everyday use. Solid nylon fibers adsorb water, which drops the Tg of the amorphous domains below room temperature to allow for their superior crush recovery. The adsorption may be small in percentage but it has a significant effect on physical properties. I suspect that hydrophobic ptex (polyethylene) will adsorb a hydrocarbon wax to some degree at the surface but it cannot penetrate too deeply as you point out due to the slow kinetics of molecular diffusion in polymers. I agree that the surface pores in sintered ptex adsorb most of the wax.
post #282 of 286

I'm well aware of the diffusion of small molecules but as you state, they don't equate to large polymers. For the sake of discussion and the intended audience, it would serve only to muddy the discussion by comparing the two. Better to stick to the point than to list the entire realm of possibilities.

post #283 of 286
Quote:
Originally Posted by Doctor D View Post

I'm well aware of the diffusion of small molecules but as you state, they don't equate to large polymers. For the sake of discussion and the intended audience, it would serve only to muddy the discussion by comparing the two. Better to stick to the point than to list the entire realm of possibilities.

I'm sure I'm not the only technically knowledgeable poster on this site, although I admit this is on the border of my knowledge. I'm much more comfortable in the synthesis of new molecules. However, my curiosity has been peaked due to my love of skiing. I've bought many of my tuning and waxing supplies from your website! smile.gif

If wax is simply filling the surface pores, why would the molecular weight of the wax, which influences its hardness, matter that much for difference waxes? Base prep wax with lower hardness and molecular weight is said to penetrate deeper into the base and enable harder waxes to be adsorbed by the prepped base. Hot boxing is said to allow the wax to penetrate deeper into the base than hot ironing. These seem to imply that the ptex itself can adsorb some wax into its amorphous domains at the surface of the base and that they are used to ameliorate the slow diffusion of wax into the base. If wax was only filling surface pores, then these would seem to be excessive treatments.
post #284 of 286

Only reason I grind my skis every 25-35 days is for structure.  I don't wax for speed, I do it because it protects the bases from burn.  White edges for those of us that are always on edge.  Besides its a great reason to have a few beers and roll a mean tyrone apres!

post #285 of 286

Revisiting this after a long time... Doctor D's thoughts echo my own regarding the wax/ski bond.

 

Regarding XLTL's question about importance of wax molecular weight -- I think this has more to do with viscosity of the wax and perhaps surface tension/cohesion. The 'thinner' the wax is when molten (low molecular weight), the easier it flows into the tiny pores in the ski base plastic.  Once the base layer is established, subsequent layers of wax are adhering to a smooth wax base, not the irregular plastic surface.  So the subsequent wax layer can be tailored to the snow conditions (as this new wax is bonding to a smooth wax layer, not the ski base).

 

Regarding the hot boxing question - this may have more to do with even heating and cooling rate and maintaining a consistent temperature throughout the ski while cooling.  If some areas of the ski cool significantly faster than others, the wax may set up differently.  If multiple types of wax are involved with different melting temperatures and thermal expansion characteristics, I can see how controlling the cooling (use of hot box) could become even more critical.* Another benefit may involve allowing time for the air in the base to migrate out of the ski and allow wax to take its place.

 

*disclaimer - I have never hot boxed a ski, so I may have this all wrong.  I am assuming the ski stays in the box until it is done cooling.

post #286 of 286
Quote:
Originally Posted by TexSkier View Post
 

Revisiting this after a long time... Doctor D's thoughts echo my own regarding the wax/ski bond.

 

Regarding XLTL's question about importance of wax molecular weight -- I think this has more to do with viscosity of the wax and perhaps surface tension/cohesion. The 'thinner' the wax is when molten (low molecular weight), the easier it flows into the tiny pores in the ski base plastic.  Once the base layer is established, subsequent layers of wax are adhering to a smooth wax base, not the irregular plastic surface.  So the subsequent wax layer can be tailored to the snow conditions (as this new wax is bonding to a smooth wax layer, not the ski base).

 

Regarding the hot boxing question - this may have more to do with even heating and cooling rate and maintaining a consistent temperature throughout the ski while cooling.  If some areas of the ski cool significantly faster than others, the wax may set up differently.  If multiple types of wax are involved with different melting temperatures and thermal expansion characteristics, I can see how controlling the cooling (use of hot box) could become even more critical.* Another benefit may involve allowing time for the air in the base to migrate out of the ski and allow wax to take its place.

 

*disclaimer - I have never hot boxed a ski, so I may have this all wrong.  I am assuming the ski stays in the box until it is done cooling.


Yes. Soft (small molecule) first, then move to harder waxes.  Better bonding, more base burn protection.  Slow long heating.  No areas that cool super quick as with ironing which are near the edges as the metal edges are a heat sink.  This assumes a ski without an edge high condition when ironing.  If edge high it is possible to overheat the edge plastic if the iron is super hot etc. 

Wax does not need to get more than about 150 F to be effective if held for a long period of time.  For SUPER hard wax one needs an iron.

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