drying time

How long did you leave it to dry? It has been my experience that it can take several days to dry completely and then the color returns to what you were expecting. Also you can leave out your first step.Simply lay the ground cover loose. Then mist spray with a mixture of dishwashing detergent and water to hold it in place.Then while it is still wet mist spray with a mixture of detergent, water and white glue. Initially it will look bad but just go away and leave it and it will dry fine.

Michael T

Normal?

What you're describing sounds pretty normal for natural scenery materials.  They do tend to get darker when glued, and the degree varies depending on the type of material being glued.  The more porous it is, the more glue it will tend to absorb and the darker it can get.  Something like sand composed of dense, hard particles will change color less than something with more clay content for example.

As noted above, final color will require the glue to dry completely.  Most of the stuff I use (glued with 50:50 white glue:water) stays somewhat darker than when it started, but becomes mostly even in color.  If you're getting a blotchy final result it could be nothing more than a characteristic of the material you're gluing.

Paints, weathering powders or airbrushing can be used to change coloration of natural dirt and rocks.  All is not lost if you don't like the results with glue alone.  Sometimes it can be beneficial to just use the natural stuff for texture and alter the color as desired after it's glued.

texture vs color

You can always go back over it with some cheap acrylics, mixed to the dirt color or your choice, as a wash and/or dry brushing.  You'll get the texture that way at least.  I've had the same problem of dark splotches but did as steamfan1211 suggested above. 

Another option is 'diorama dirt' from monster models.  I think on my layout's lighting it looks too much like beach sand, but I do have uses for it on there.

"dirt is significantly darker after it's glued down"

    That's normal and can be adjusted by adding a bit of light colored grout to the dirt. Experiment with small batches till you see how it works. Optionally just airbrush it after it dries to color it more to your liking.....DaveB

If you don't object to some

If you don't object to some dirt being loose, you can add a thin layer on top of the glued portion. 

I get significant darkening after gluing with the real iron ore I use, which is fine for freshly excavated ore, but not for the mining roads.  I come back after the glued material is dry, and dust on very fine ore, which lightens everything up nicely.

This is what I do. I use some

This is what I do. I use some brown latex paint, lay down a thin layer of the paint. While the paint is wet, I pour the dirt over the latex paint with lots of dirt. There will be some dirt that never gets into the paint, just vaccum that dirt up. As long as you put enough dirt over that, the dirt will be lighter in color.

You can see how light colored the dirt is in the foreground, when I used this process.

If it stays too dark, I'd

If it stays too dark, I'd suggest cheap art pastels, scraped with a blade to make a nice pile of powder, gently applied with your fingers. A selection of earthy light browns and greys help you keep the soily look.

This is over painted water putty, not soil, but the principle's the same

Durham's Water Putty

Thanks...

I appreciate all of your suggestions, but right now, I'm liking Chris's the best.  To me, one of the advantages of using real dirt is the subtle variations in tone and texture that occur naturally--no paint or other additional coloring required.  If the Water Putty still lets that through, it could be a winner.  Mike's technique with the pastels sounds good, too, but sounds like an awful lot of work if a large area is involved.

Jeff

I have some Durham's

but have yet to use it.  Shoofly, can I see some pics (mixed with dirt I mean)?

Photos

Here are some photos, the hill cut exposing the dirt is what it looks like.

Chris

Re: Chris

That's some most excellent dirt and ground cover.

Thanks Rob

Look into Zip texturing

Look into zip texturing as well. Just use our new MRH google search (upper right) to search this site for the term:

zip texturing

One huge power of zip texturing is the ease of getting exactly the dirt color you need, matched to photos.

Almost always, using real dirt on an indoor layout will have darkening problems. Zip texturing lets you make your own dirt of any color you need and match it to photos precisely.

Shameless plug

Let me also make a shameless plug for TrainMasters TV here ... for $5.99 per month (or as little as $3.33 / month if you opt for the gold annual sub) you get access to the entire Siskiyou Line video series, including the Tenmile Creek scenery step-by-step where I illustrate extensively how to do dirt color and other scenery color matching to photos.

Just go on over to TrainMasters TV and sign up ...

Like I said, shameless plug!

...

Use a different dirt.

Depending on the dirt's source, every dirt will change color differently.  Some get darker, some don't.  At SASME, the dirt is substantially different at the parking lot slope versus across the street where it's undeveloped land - 20 feet makes a PROFOUND different on the layout!!  The undeveloped land provides a much lighter shade, while the former is a much darker shade.  I will also go back over a finished road and layer on a coat of thin dust, then vacuum it off just to remove the overlay.

Once you find a good source, note it.  I get my landscaping dirt from the southwester corner of Winsett and Pace Court, and my road dirt from the north western corner of 7th Street and Fremont.  Yes, i am that specific on my dirt sources!!  And now I have this new source, out in front of the club for shade three.

Always try and test new sources before you do large areas.  What looks good up front may indeed be all wrong once you put it down.

Hair Spray

This anomaly really bugged me too.  Especially being able to see the "tide marks" where you left off the day before. Excellent idea posted where you sift the dirt into wet paint of the same color.  What works well for me.....get some cheap hair spray at the Dollar Store and spray the area in question, then sift on a light coating of dirt.  It will not change color.  Another tip.........hair spray works better than white glue and water for static grass applications.

Too Much Clay

I have found the problem is in the clay content.

We use "DG" Decomposed Granite out of the desert... We bake all of the water out of it.
When applied as a scenery base it dries the nice light color it looks like before applied.

Our Diorama Dirt is based on this... but anyone can make it...

Keep off the baseball diamonds and pitchers mounds... too much clay and the kids can trip in your holes... ha.

Jimmy Simmons
Monster Modelworks

Glue first, no bonding after

A correction

Earlier I posted the DIo Dirt was too beach-sandy under my layout's lighting.  I was wrong!  Last night I did some late-nite scenery work over a few large areas and found it was not the dio dirt that was too light/yellow/sandy/whatever, it was in fact some locally-obtained BB diamond dirt.  I ran out of my pre-baked local dirt, grabbed a can I thought would do the same (after applied I thought it would darken to the same stuff I had been using) and also applied the dio dirt to a different long stretch.  The dio dirt was correct for the area and what I expected (but apparently forgotten in a prior test), and the spare can of local stuff as applied now has to be attended to.

There really is allot to be said for labeling your cans, and also making a note of "what is where, and in what order if layering your dirt".  I thought I knew what was where, but when I ran out.....!

darkening

This happens to me 100% of the time.  Bob Lawson who has built more dioramas than I have freight cars , says the trick is to top coat some additional sifted dry dirt on top of the glued dirt.  Don't do this while the surface is totally liquid.  You must add enough that the surface of the new coat does not darken.  When it dries you may leave the surface dust or vacuum it off.  After vacuuming, a very thin dry crust of light dirt will remain.  I have had good success with this when I have the patience.  Otherwise, I get the paints or other techniques going as stated.  There are many ways to "skin a cat"  John Miller K&LE RR

How are you applying the dirt?

We use sifted real dirt at the club (we couldn't afford synthetic given the area we have to cover even if we wanted to use it). What we do, which seems to work pretty well, is paint a white glue/water mixture (1 part glue to 2 parts water) then shake the dirt onto the painted area. The first fine layer gets saturated with the glue/water and does darken, but the dirt above sticks to it and doesn't discolor. Then you lightly vacuum off the loose dirt. I also used this technique on a 13 square foot layout I built for a micro-layout design contest. The dirt is the same color it was when I gathered it from part of the Redlands Loop in San Bernardino County.

An inexpensive alternative for "real" or purchased dirt

I make my own "dirt" using common plaster.  I add water based concrete colorant directly to the water and then poured the plaster in a thin coat on a piece of non-stick foil.  After it dries I take it off the foil and break it up with a hammer.  I then use different screens (even down to one of my wife's discarded stockings) to get the different "grades" (sizes) of material.  I do find that the color changes slightly when glued down; however, I test and adjust colors in advance before using the materials on my layout.