I've not used cat litter for this application. Instead, I tried to color match the Kato plastic with a Woodland Scenics color ballast. Looks good enough for what I am doing. Although cat litter would be cheaper.
I'd avoid cat litter as it will clump when it gets wet. And you'll need to get it wet to glue it down. Plus cat litter is in too large of pieces, that it will look like small boulders are being used for ballast.
I'd definately second what Ike said about cat litter dissolving, and also point out that whatever brand of ballast you'd choose to use (I'm planning to go with Arizona Rock to better match prototype color) you'll be using a relatively small amount to just cover up the molded "ballast" so a single bag of scale product should go a long way.
If you're more concerned about cheap, inexpensive "something" to represent your ballast, then by all means use non-clumping kitty litter. I'm sure it'll look like hell, but it won't cost you much! Even cheaper, but maybe better looking, would be to go to your local gravel pit with a shovel and see if you can find some dirt that looks to be about the right color for your ballast. Dig a couple of buckets of it from places that have different colors and try to not get too much big stuff. Take your dirt home, put some of it in a metal pan and cook it for an hour at 400 degrees or so to kill any organic things in it and to sterilize it. after it's cool, sift it through several sizes of screens (wire colanders are good) with the final "sift" being a tea strainer. The dust that'll go through the tea strainer is good for a lot of things scenery-wise, such as cow/deer paths, dirt roads, etc., so keep it in a container you can fasten the lid down on. After you've sifted your dirt into several "grades" or sizes of stones, shake a cow-magnet or two around in them to get rid of the ferrous materials, which will stick to the magnet. The sifting process should get rid of most of the obvious organic stuff. Remember that real mainline ballast is usually composed of rocks in the 3" diameter range. Take a micrometer and measure your piles of sand, and choose the one that's got dirt particles of around 20 thousandths of an inch. You don't want it to be monotone, so mix your two colors of sand together to get a color and texture that you like. I did the same thing with my N-scale Highball real-rock ballast, both sifting it and mixing three colors together to get the right "look" for my UP mainlines. I used straight "cinders" for the branchline, which looks just right. About the cat-litter. Don't use it...it's clay and you want fine sand. I also don't recommend Woodland Scenics ballast, although some modelers really like it. It's made out of walnut shells or something like that. I prefer "real rock" ballast by Highball or Arizona Rock & Mineral. There's another couple of companies that do real-rock, but I can't remember their names. I'm sure someone will chime in. Cheerio! Bob Gilmore
The woodland scenic fine gray ballast is what I use. I just use it on the shoulders of the roadbed to get rid of that steep angle of the plastic. I usually tone down the shine on the plastic before ballasting with Isopropal Alcohol with some India Ink. I ballast out to about 3/8ths of an inch from the base of the plastic and taper it up to the top. I paint white glue to hold a light coating of the ballast to the plastic then come back when it has dried and add the rest, using alcohol to wet it up and diluted white glue as the adheasive. Cat litter would be good for garden layouts.
Like mentioned in the other forum you posted on. I second this method as it is what I intend to do. Sent from my Galaxy Nexus using Tapatalk
Kato Unitrack is already ballasted. If you're adding ballast to improve its appearance, then cat litter will do just the opposite, and make a mess to boot. Follow the recommendations already posted. Another option is to go to a craft store and get fine colored sand--it's really cheap. Some modelers use it with good results. Best to get a couple shades of grey, if possible, to blend together.
Just a heads up since many people arn't aware....Kato does make matching ballast. 24-039 'Unitrack Ballast-Fine Grain; colored to match Unitrack' I'd stay very far away from cat litter for ballast personally. Enjoy! Kelley. www.dufordmodelworks.com
Here is a link for using Woodland Scenics to match Kato ballast. http://thomas.tuerke.net/on/mrr/?thread=1289869264 Works well
I myself have tried this method & it works well, Just using this ratio or a little experimenting on your own, you just about can't go wrong.
Kato ballast is more expensive than the same amount of woodland scenic ballast. The fine gray color is very close and looks good.
I purchased two bags of Arizona Rock & Mineral from my LHS. The stuff is like $5-7/bag. I bought two bags, but I'm realizing one bag is plenty for my layout. Is a bag of kitty litter much cheaper than that anyways? I'll happily pay ~$10 to get ballast that I know I'm going to be happy with. IMHO, these cost saving measures just don't seem to make financial sense. Here's a couple shots of my Unitrack ballasting: First did a sample on some scrap wood
Good thinking! For many years, I have urged people if unsure, or needing practice, to try this method. Your results look very nice!