Filling Cracks In Old Railroad Ties ?

Not a good idea...filling the cracks/checks won't stop moisture but it

Not to mention that railroad ties are not the best thing for garden borders. Particularly not for vegetable gardens. Take your idea into the rec.garden group and see what their advice is.

You are probably out of luck - I know of nothing that will do what you want and last for a long time. Epoxy would do it but also trap moisture and eventually fail. Plus - It will cost more than just getting new landscape timbers or some other type of edging.

. Plus - It will cost more than just getting new landscape

Not the 3 x 5 landscape timbers from the typical big box stores, please. They're termite magnets and not up to long term use. -- Regards --

I'm going to experiment with concrete to fill the cracks of some of the ties I'm building a wall with. The concrete will be porous and allow small amounts of moisture out and possibly look pretty cool with Grey veins in the wood.

One challenge is that it might crumble but the wall I'm building will be stationary. I'm not suggesting this as advice because I still haven't put it to practice just something to consider.

Just have to find something that will fill a crack and dry with some pores.

I would look for a construction adhesive or mortar repair type product in a tube. It will be flexible, stick very well to the wood and be easy to apply.

Is there a modern day version of creosote?

IDK, he seemed to like the idea of a concrete like color. If he wants something creosote like and that color, then a caulking gun tube of one of the roofing tar like products sounds good.

Bondo All-Purpose Putty, Designed for Interior and Exterior Home Use, Paintable, Permanent, Non-Shrinking, 1.9 lb., 1-Quart

I used this on an old cracking threshold. Worked good.