Polarization is done by rotating two gratings. It uses the electro-mechanical propers of light to create the affect. The gratings are sandwiched between two pieces of glass. In other words, polarizers are built using 2 gratings and 4 pieces of glass in a rotating frame. Each grating is sandwiched between two pieces of glass. If the edges are not sealed, liquids can be drawn up by capillary action into the spaces between the grating lines. This will render the filter to junk. This is one of the reasons for the Kaesemann design (not the only one). B+W is one of the only manufacturers of such. That design will allow a drop of oil or soapy water since the sealed edge prevents any capillary action. I still would not suggest oil or soapy water since it could still get into the space between the two glass / grating sandwiches. Taking the filter apart is actually the best way to correct the problem, Kaesemann design or not. Otherwise, one uses the filter as is or, as some have suggested, one throws it away. I haven't priced it, but I would think it would be slightly cheaper to take them to the camera repair shop rather than buy new filters.

One correction about my description of polarizer construction: the filter with two gratings is actually for variable neutral density filter. With a standard polarizing filter, the first "grating" is the polarization of light by Mother nature. The "second" grating in the filter then blocks a certain directionally polarized portions of the light. With a variable density filter, all the light is polarizer in one direction by the first grating and then the second grating starts blocking the polarized light as the front portion of the filter is turned. Same basic principle for both types of filters. It is just that mother nature rarely polarizes all the light in one direction. This allows one to choose which polarized reflections to block. Still doesn't change the grating "sandwich" and whether or not the edges are sealed. But the capillary action is only stopped by sealing the edges.

WOW, I did find an article that purports two pieces of glass in a polarizer filter, with one rotating!!!
"How do I use a polarizing filter?
Most polarizers are circular, screw-in filters. A polarizing filter is actually two pieces of glass put together. The front piece rotates, while the other piece doesn’t. Rotating the front of the filter will change the intensity of the reflections, or the intensity of the color saturation effect."
https://www.shawacademy.com/blog/ultimate-guide-polarizing-filters/

And this about the filter constructed of sandwiched optical elements:
"The polarizing filter features a dichroic absorbing layer sandwiched between two layers of glass."
(Would the "sandwiched" elements really have a capillary action to get a liquid between them.
I suppose it depends on the sandwiching method.)
https://ascmag.com/blog/shot-craft/understanding-polarizing-filters

I'm guessing ONE of these articles is correct.
My money is on the second......

And this is how bad information keeps propagating, I saw it on the net. But that's another comment in another thread.

WOW, I did find an article that purports two pieces of glass in a polarizer filter, with one rotating!!!
"How do I use a polarizing filter?
Most polarizers are circular, screw-in filters. A polarizing filter is actually two pieces of glass put together. The front piece rotates, while the other piece doesn’t. Rotating the front of the filter will change the intensity of the reflections, or the intensity of the color saturation effect."
https://www.shawacademy.com/blog/ultimate-guide-polarizing-filters/

And this about the filter constructed of sandwiched optical elements:
"The polarizing filter features a dichroic absorbing layer sandwiched between two layers of glass."
(Would the "sandwiched" elements really have a capillary action to get a liquid between them?
I suppose it depends on the sandwiching method.)
https://ascmag.com/blog/shot-craft/understanding-polarizing-filters

I'm guessing ONE of these articles is correct.
My money is on the second......

And this is how bad information keeps propagating, I saw it on the net. But that's another comment in another thread.

WOW, I did find an article that purports two pieces of glass in a polarizer filter, with one rotating!!!
"How do I use a polarizing filter?
Most polarizers are circular, screw-in filters. A polarizing filter is actually two pieces of glass put together. The front piece rotates, while the other piece doesn’t. Rotating the front of the filter will change the intensity of the reflections, or the intensity of the color saturation effect."
https://www.shawacademy.com/blog/ultimate-guide-polarizing-filters/

And this about the filter constructed of sandwiched optical elements:
"The polarizing filter features a dichroic absorbing layer sandwiched between two layers of glass."
(Would the "sandwiched" elements really have a capillary action to get a liquid between them?
I suppose it depends on the sandwiching method.)
https://ascmag.com/blog/shot-craft/understanding-polarizing-filters

I'm guessing ONE of these articles is correct.
My money is on the second......

And this is how bad information keeps propagating, I saw it on the net. But that's another comment in another thread.

Wikipedia is much more detailed: both the articles you cite are correct depending on which type of method of polarization. One more quote to let your mind chew on:

"Wire-grid polarizers

One of the simplest linear polarizers is the wire-grid polarizer (WGP), which consists of many fine parallel metallic wires placed in a plane. WGPs mostly reflect the non-transmitted polarization and can thus be used as polarizing beam splitters. The parasitic absorption is relatively high compared to most of the dielectric polarizers though much lower than in absorptive polarizers."

Key here is "One of the simplest". A circular polarizer has a linear polarizer followed by a quarter wave glass plate. And there are other types of ways to creative the necessary polarization. But the fine wire grating is one of the simplest.