Long story short. I use ballast from a company in Tukwila, Washington called Manufacturers Minerals. The ballast I use is not #4 dust (or 1/4" minus) but a clean washed rock that they call “Bridge Topping”. A few other local railroaders use the same stuff (Paul Burch & Dave Goodson come to mind). For years, I’ve wonder what exactly this stuff is, why it’s made, and how someone on the East Coast could replicate this stuff as it looks really good for scale ballast. Not so much for structural ballast. When I buy it in 50 pound bags, it costs a whooping $5.50. Yes, that’s right. $5.50 for a 50 pound bag.

Anyway, I called the company to ask them the hours because I need to pick up another couple hundred pounds and asked what size this rock is. The lovely gal responded by calling it a 4x8, while other companies produce a 6x10. So with that information, I started researching rock sieve sizes… Low and behold, #4, #6, #8, and #10 are all standard rock sieve sizes.

I came across this handy chart. https://www.globalgilson.com/sieve-sizes

Thus, now I know exactly what size rock I’m getting, and you too can replicate at your house by simply sifting some #4 dust (or 1/4 minus). Happy sifting. Meanwhile, I’ll just go buy some bags of rock.

I’ll try to add a picture of my ballast so you can see what it looks like.

Around here it’s commonly referred to as “screenings”, 1/4 minus or paver base. Where I first came across the stuff was when I was working for the phone company and had conduit crews placing conduit for us. It was used to back fill the trench. It was light and loose and filtered around the conduit nicely. And also acted as a warning if there was any future digging. It’s also used by Hardscape landscapers as a base under pavers used for walkways and patios. A pickup truck load is about $15.

Lowes also sell it in 50 lb bags but it has the occasional larger stones in it. It’s found in the Hardscapeing department.

A few years ago I had a crew replacing our front walk and they a bunch of the stuff that was left over. I’ve been gradually diminishing the pile by using it on the layout.

(That’s not my walk, BTW)

Ken Brunt said:

A few years ago I had a crew replacing our front walk and they a bunch of the stuff that was left over. I’ve been gradually diminishing the pile by using it on the layout.

(That’s not my walk, BTW)

For a second I thought you might have won the lottery and re-done your back walkway (https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-surprised.gif)

Around here they call the stuff Ken buys “Stone Sand”. I buy 1500# at a time from the local trans-load depot where they unload numerous grades of stone from trains and load into dump trucks from stockpiles. It costs me about $20 a load (exact change / cash only!) to fill a small trailer. I still have a lot left from a buy 2 years ago.

For display tracks and/or photo shoots I sift it through an old terrarium top to remove the dust. Looks darn good as it comes and perfect when sifted.

No, Ken this stuff I’m talking about isn’t mixed with fines. It is clean. The stuff your talking about has fines mixed in with it.

Yeah big difference without fines… you can see the dust cloud around the tamper the woman is using.

Technically the rocks are about 3 scales inch too big, but I think the look is there. Any smaller, and I think you lose the look. Next time I go get rock, I might ask if they have a bigger sieve size combination just to try out. And maybe a bag of something bigger to use as rip rap.

Craig Townsend said:

No, Ken this stuff I’m talking about isn’t mixed with fines. It is clean. The stuff your talking about has fines mixed in with it.

Ah ha! I’ve never seen that stuff. Thanks for the heads up.

Ken Brunt said:

Craig Townsend said:

No, Ken this stuff I’m talking about isn’t mixed with fines. It is clean. The stuff your talking about has fines mixed in with it.

Ah ha! I’ve never seen that stuff. Thanks for the heads up.

There is some sort of industrial use for this product. I think it is used as a grip surface for asphalt chip seal. Or applied on road bridges.

The gal I talked with implied that the normal size is 6 x 10 which actually is smaller rock. Given that Washington State isn’t the only state out of 50 with paved roads and bridges, this stuff should be available more locally. Although, flat rate boxes could stuff a few pounds of it in.

Getting more technical here now...

Class 2 trackage has ballast 1.5" to 1" rock. So that is .051" to .034" if we use 1/29 scale...

Now roaming the sieve size chart that gives us a sieve size of 14-20. So clearly the #4 and #8 stuff that I'm using is way oversized. Now I should see if they have smaller stuff.

https://www.sigmaaldrich.com/chemistry/stockroom-reagents/learning-center/technical-library/particle-size-conversion.html

Craig Townsend said:

Ken Brunt said:

Craig Townsend said:

No, Ken this stuff I’m talking about isn’t mixed with fines. It is clean. The stuff your talking about has fines mixed in with it.

Ah ha! I’ve never seen that stuff. Thanks for the heads up.

There is some sort of industrial use for this product. I think it is used as a grip surface for asphalt chip seal. Or applied on road bridges.

The gal I talked with implied that the normal size is 6 x 10 which actually is smaller rock. Given that Washington State isn’t the only state out of 50 with paved roads and bridges, this stuff should be available more locally. Although, flat rate boxes could stuff a few pounds of it in.

Way back when, they used to tar and chip the roads. I haven’t seen that done in a long time. But there could be places that still do.

You get any smaller and you’ll end up with sand…(https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)

Get too small and you’ll end up with sanded parts inside your locos …(https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-surprised.gif)

Rock products tend to depend on what is in the ground locally.

I harvest coarse desert sand and winnow out the fines.

When it falls to the ground off my elevated track, there is no clean up necessary.(https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)

Last night I was showing off my layout to my Dad, a retired Civil Engineer. He took one look at the ballast and said that’s too big for railroad ballast. So, I pulled out my scale ruler and sure enough it was about 5-6" scale. With that little tidbit, I called the company and asked them what size rock was in this material. The receptionist replied 4 by 8. Armed with this information, I found a rock sieve chart online and low and behold the #4 size sieve had an opening that was around 5" scale. (1/29 = .034" scale inch; #4 sieve is .187; which makes the biggest rock 5.5" long)
https://www.sigmaaldrich.com/chemistry/stockroom-reagents/learning-center/technical-library/particle-size-conversion.html

Then, I started looking up classifications for class 1 and class 2 trackage and ballast size. BNSF produces a nice handy little chart that gives the specifications for class 2 trackage (industrial). Since I’m modeling a branchline, I figured class 2 trackage should be a good start.
Class 2 Trackage should have the following: 100% 1.5". 90-100% 1", 40-75% 3/4", 15-35% 1/2", 0-15% 3/8" and 0-5% 0-Number 4 Size Rock

With that information gathered it was an easy step to convert those 1:1 sizes to scale sizes, and I got something along the lines of this;
100% .051"
90-100% .034"
40-70% .025"
15-35% .017"

Now the next step was converting that to sieve sizes…
100% #14-16
90-100% #18-#20
40-70% #25, #30
15-35% #40

With that information, I called back the same company and asked if they had a product that was available between a #14 and #20. Still waiting to hear back so see what they say. Worse case, I can always go back to the oversized rock I started with and call it good. At $5.50 for a 50 pound bag of rock it is cheap enough to play around with. The other thing I have to consider is the this oversized rock won’t wash away as easily as the smaller stuff, but I still expect to have to refreshen the ballast after every winter. Oh the joys of modeling outdoors. I may experiment with creating a glue mixture with Titebond III wood glue which is supposedly “water proof”.

I wouldn’t worry too much about the size, eventually the ballast disappears anyway. …(https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)

Ken Brunt said:

I wouldn’t worry too much about the size, eventually the ballast disappears anyway. …(https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)

Yep. It is a yearly reballasting thing. I’m tempted to try glueing some down and seeing what happens. I’ve heard Tightbond III is waterproof?

Craig and others,

Craig, Be careful about gluing down the ballast. If it is over solid roadbed like concrete it will work. Just don’t get it up on the ties where it can stick the rail to the ties. Gluing the ballast where it is over dirt will not work. Winter freeze thaw will cause it to lift and look real bad.

Here is a photo of some track with the bridge topping that Craig has mentioned. I use liquid concrete strengthener from Home Depot in places where I can get away with gluing. I don’t believe any of it is glued in this photo. Buy it by the gallon, It looks like white glue. I put it down using a condiment dispenser like used for ketchup. But like I said, only on solid roadbed and usually only on the outer edge of the ties. It is waterproof when dry.

Ken Brunt said:

I wouldn’t worry too much about the size,

Um, ah…yea.(https://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-embarassed.gif)

David Maynard said:

Ken Brunt said:

I wouldn’t worry too much about the size,

Um, ah…yea.(https://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-embarassed.gif)

You forgot the relevant part for us old farts…(https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)

Ken Brunt said: disappears anyway.

Around here, in Eastern Washington, the smallest I’ve been able to find is 5/8 inch minus. I’ve asked various rock dispensers if i can get the rock without the dust, no joy.

I worked for a time while in college for the Idaho Dept of Highways, doing this and that. One of my jobs was inspector on a rock crusher. We had a jig with various grades of openings to filter out the sizes. I built one, using 2 x 4s and 1/4 inch hog wire. Everything that goes through gets used as automobile roads, what doesn’t, becomes ballast top dressing. It’s oversized, but not too bad. It passes the 10 foot rule.

Edit; It really sucks when you have to edit Bill Gates mistakes!

I have found some 3/16 size stone called rice stone , not pee stone either .