First, don’t use them in damp places like unheated cellars, garages, or sheds. They will mold. Use grinds only in heated structures.

Now to business. Put them in a baking pan and stir them well. Then take a potato masher and break up any clumps. Spray with Lysol and stir again.

Then bake in an oven (I have gas) at 300 degrees for 30 minutes. No longer, as they will start to smoke and perhaps even burn in the over.

Then bake then again — with Lysol added — at 300 degrees for 30 minutes.

Now place them in jars and keep an eye on them. If you see white spots, toss the jar. That’s mold.
If you just see clumps, there is still moisture in the grinds. Bake again — with Lysol added!

A prolific writer for Model Railroaders said that should do it.

OR, buy a bag of play sand (very fine grains), dye them with diluted acrylic paint, india ink, or whatever, spread them out to dry, then ballast.

Good luck,

George

I tried air drying but the mold was a bear. So I baked the stuff, in a baking tin, for 35 minutes at 300 degrees. It worked for most of my samples, which I put in glass containers (NOT opaque containers). But one day, I saw mold in one of them, with some of the grinds in little lumps, so now I bake TWICE at 35 min and 300 deg.

If you try this, watch the baked grinds. If you see just very fine grinds throughout the glass container you are good to go. If you see whitish grinds or they are lumped together, you still have a moisture problem.

I like the Lysol idea, but I wonder whether to grinds have mold problems on a layout. I’d only try them on in-house layouts, not in unheated rooms like garages or sheds.

Good luck.

George

I suggest that you bake your grounds in a medium oven for 30 minutes or so. This will finish the killing as well as drying he grounds completely. Being bone dry will help them absorb more glue water and stay in place better. In addition to the dish detergent, add a little Lysol to your ballast liquid. That will provide some ongoing disinfectant protection which alcohol can’t do as it evaporates too readily. You might want to add just a slight gloss to the ballast in the center of your roadbed to represent the latest drips of oil and gunk.