One of my newest and most pristine Northgate Omnikey 101 ANSI SKCM White Alps keyboards doesn't sound and feel quite as good as my older Omni 101s. The only difference in construction that I can find is that the newer board has "bamboo" (no slits) switches, whereas the older boards have "pine" switches (with slits in the top housings).
Therefore, I've decided to mod the bamboo switches by replacing at least the top housings with pine housings from an Orange Alps board. I am going to keep the White click leaves, but I am undecided about the other swappable components (slider and return spring).
Sliders from Orange Alps are factory-lubricated, but because the switches are old, I decided to give them a thorough cleaning in an ultrasonic cleaner, which of course removes the lubricant. After doing this and looking for similarities and differences among different types of sliders that I have at hand (Blue Alps, Orange Alps, White Alps, and Matias-Click), I noticed a subjective difference in slipperiness among the sliders. By pressing a finder against the slider and pulling my finger across it, I felt more friction with the Orange and Blue sliders than with the White and Matias sliders.
However, I wanted to get some quantitative indicator of slipperiness, so I rigged up a simple experiment to measure the coefficient of static friction. This consisted of a smooth plastic ruler as an inclined plane and a second ruler clamped perpendicular to the desk. I placed the slider at a fixed spot on the plastic ruler and slowly tilted the ruler until the slider slid down the ruler. I measured the distance on the vertical ruler corresponding to when the slider broke free of friction and slid down the incline. Thus knowing two sides of a right triangle, I could calculate the angle of tilt and its tangent, which is the coefficient of static friction. I did this 5 times for each slider, calculated the mean and standard error of the friction coefficients, and plotted the results:
(Attachment Link) I also ran one-way ANOVA and the Tukey post-hoc test to find statistically significant (p < 0.05) differences. In the above chart, if two values are significantly different from each other, they have different small letters above the bar. A lower mean value corresponds to a lower coefficient of static friction (more slippery).
The results show that Blue and Orange sliders do not differ significantly in static friction. White sliders are more slippery than either Blue or Orange, and Matias-Click sliders are the most slippery.
This was a very crude experiment and YMMV, but it showed me that my subjective qualitative impressions were validated by this rough quantitative measurement.
I am not quite sure how to interpret the results, but they might provide an explanation for why Blue and Orange Alps switches were apparently factory-lubricated.