I'm looking for a leather holster for my Ruger GP-100 4.2", and I have run across a few new ones I am moderately interested in. Some I see have an acrylic sealer. What does that actually do? Do I want that? How do you care for it? etc.

I'm used to old school leather care like saddle soap and shoe polish (wax based) and if warranted a local product About Us - Skidmore's I contacted them, and they specifically told me it won't soften or loosen a molded holster.

Sealant is frequently applied to holsters and other leather gear as a means to prevent moisture infiltration. All leather articles will readily absorb moisture from the atmosphere, from the user's body, from perspiration, etc. Acrylics, particularly water-based acrylic lacquers, have been widely used for this purpose, and (IMO) do a good job.

Nothing is absolute, and nothing is absolutely permanent. Normal use and wear will expose leather fibers, thus compromising the sealant. That is where the routine maintenance becomes important. Applications of wax-based products can maintain the appearance and enhance the moisture resistance of the finished piece. Neutral shoe polish is probably the most commonly available product, and it performs very well without degrading the integrity of the holster's forming and fitting. Oil-based products or greases tend to infiltrate and collect, over time causing the leather to become more supple and limp.

For most folks a small can of Kiwi neutral shoe polish should be all that you ever need for routine maintenance. Very light application with a soft cloth, then buff the surfaces with an old towel or T-shirt.

Most of the saddle soaps I have seen in the past 20 years or more consist of high levels of glycerine soaps with some beeswax. The glycerine can penetrate and accumulate, eventually causing the leather to soften to an undesirable degree.

OK, so use saddle soap sparingly, if needed, and wax shoe polish, usually neutral, to protect the surface, and seal out moisture. Were this a wet environment situation, I'd go stainless pistol and Kydex, but its not.

Any insight on some of the properly formulated leather preservatives some here rave about?

Feibings Resolene (an acrylic) has been a very popular and commonly used sealer for decades. Works great for holsters. The polymer coats and protects the holster against moisture. It is quite durable and long lasting.

Leather preservatives / conditioners should not be used on most holsters... neatsfoot oil, mink oil, etc. when applied to excess will soften the leather. Neutral shoe polish is ok. Or, simply reapply the acrylic.

Resolene - Fiebing's

Fiebings has been in business for well over a century and makes a variety of sealing / finish products. Saddle-Lac, Bag-Kote, Tan-Kote, etc. all work. Don't overthink this. Buy a good sealer, apply as directed and move on. Just stay away from the oils and conditioners.

Good luck.

Muzzle Blast has it right.

Resolene works fine. Rub it on with a soft cloth or piece of sheep’s wool until it isn’t wet any more. Let it dry over night and buff it with a clean soft cloth. Repeat when ever it starts to darken with sweat etc,

Neutral shoe polish also works well, you’ll just need to apply it more often.