Trains.com

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Rock Coloring Advice/Tips

1526 views
15 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    December 2020
  • 4 posts
Rock Coloring Advice/Tips
Posted by Toth on Monday, March 8, 2021 12:02 PM

Hi - Can anyone offer any step-by-step suggestions on how to achieve rock colors that look similar to this? I'm working directly on foam, but even suggestions of how to achieve this look on plaster/hydrocal rocks would be helpful. I'm not even sure what the base color should be. I've tried gray, white, tan, etc. but my results are pretty miserable. I serached the forum, and the internet prior to asking, and I haven't found any step-by-step guides. Any suggestions are welcomed. Thanks in advance!

Image 001

Image 002

Image 003

Image 004

  • Member since
    August 2006
  • 1,352 posts
Posted by trainnut1250 on Wednesday, March 10, 2021 3:02 PM

Welcome Welcome to the forums!!

In looking at the photos - those appear to be hydrocal castings. There are two basic approaches to coloring them: one is to seal the plaster with a base coat of paint or sealer to make it nonabsorbent and then color over the sealed rock casting, the other is to let the pigment soak into the unsealed casting and use the plaster as the “white” in color blend. I’ve used both methods but prefer the latter.

Woodland Scenics sells some earth pigments that contain the colors you are looking for in those photos, They also sell a nifty little scenic “how to” book that describes the “leopard spot” approach to coloring castings. I have used water color paints with ink and alcohol washes along with acrylic pigments to color castings as well.,

Working on raw foam may not give you a good surface to create rocks. I would apply castings on the foam or carve and then seal the foam with a coat of plaster (paint it on so you won’t obscure the carved rock detail) or maybe paint on thick paint or gesso to create a smooth surface.

To create the rocks in the photos you will likely need some rock molds – WS or Bragdon sell them – much easier than carving (from someone with extensive experience carving rocks in plaster). You might check out Malcom Furlow’s work on some of his project layouts for MR (San Juan in particular)where he used foam to create rocks – he was modeling the sand stone spires in the south west and the foam had the right texture to successfully replicate those rocks.

Good luck with the project,

 

Guy

 

 

 

see stuff at: the Willoughby Line Site

  • Member since
    February 2018
  • From: Flyover Country
  • 3,037 posts
Posted by York1 on Wednesday, March 10, 2021 3:30 PM

Toth, welcome!  Your first posts are moderated and won't appear immediately, but don't give up.  After several posts, it will be normal.

I have not been in model building very long, but I got valuable advice that worked from someone on this forum.

They told me to paint everthing black first.  Then start working up lighter colors from there, but leaving the cracks and crevices black.  The lightest colors came last.

That said, I'm sure that some on the forum would give the opposite advice.  But it worked for me.

It took a lot of work and a lot of blending colors before I got the look I wanted.  I actually used about eight different colors blended in different amounts and irregularly brushed on to get the effect I wanted.

 

This is your image number 2:

 

Checking closely it looks like there are six or seven different colors on the rocks.

 

Good luck, and let us know how you do.

York1 John       

  • Member since
    December 2015
  • From: Shenandoah Valley
  • 8,035 posts
Posted by BigDaddy on Wednesday, March 10, 2021 3:44 PM

York1
Checking closely it looks like there are six or seven different colors on the rocks.

Is that a bad thing? 

This is Sideling Hill in MD

Henry

COB Potomac & Northern

Shenandoah Valley

  • Member since
    February 2018
  • From: Flyover Country
  • 3,037 posts
Posted by York1 on Wednesday, March 10, 2021 4:12 PM

BigDaddy
York1
Checking closely it looks like there are six or seven different colors on the rocks.

Is that a bad thing? 

 

I didn't mean to make it sound like a bad thing.

I meant that it's difficult to pin down one or two colors for rocks when, in actuality, just about every rock surface has many colors.

That's why I used a bunch of colors, and a bunch of different blendings, to get a more realistic look.

York1 John       

  • Member since
    July 2006
  • From: Central Vermont
  • 4,404 posts
Posted by cowman on Wednesday, March 10, 2021 4:32 PM

Welcome to the forums.

A little expeerimentation is probably in order.  There are a number of ways and some work better for some, where another works better for someone else.  Also different types of rock can take different methods.

A student I mentored was shown this method by his previous teacher and it seemed to look pretty good.  He just took a screwdriver, stabbed and gouged the edges of the foam.  Then he used a medium gray paint over the whole thing, adding washes later to highlight

I have a foam based layout and I used Sculptamold and plaster in molds for my rocks.  I used commercial molds, ones I made with WS Latex Rubber (picked  up local rocks to look like local rocks) and heavy duty aluminum foil, crumpled then smoothed  out, made nice looking rocks.  Mine are mostly gray based rock, so I used india ink and alchol washes.  Let each application dry before you deside if it is dark enough.  For brown rocks I'd get the sepia colored ink.  Some rocks around here are nearly black, I'll have to experiment to see if I need to paint or if a strong india ink will do it.  The one negative I have heard about a painted basecoat (sealing the plaster) is that if it chips, the white plaster shows more than stained plaster. 

Have fun,

Richard

  • Member since
    November 2002
  • From: US
  • 2,425 posts
Posted by wp8thsub on Wednesday, March 10, 2021 10:20 PM

To get a similar look to your photos, I start with a wash of black acrylic.

Wall Wash 1

by wp8thsub, on Flickr

The black provides a base stain color but isn't necessarily opaque.  If you're starting with foam as opposed to plaster, you could use black or dark gray latex paint instead, and apply a coat over the whole area.

Wall Color 2

by wp8thsub, on Flickr

Next, I dry brush two or three progressively lighter colors of acrylic craft paint. The final color is usually very light, but I don't use white.   Choose several shades of related colors based on darks and lights in the scenery photos you're working from.  I'd suggest using prototype photos instead of models when looking for paint. 

Lakeview Scene 2

by wp8thsub, on Flickr

Finally, I use the same paints on any natural materials like talus, waiting until after they're glued down.  Painting the real rocks blends them with the plaster rockwork (or foam if you're using that).

Rob Spangler

  • Member since
    November 2013
  • 1,613 posts
Posted by snjroy on Thursday, March 11, 2021 9:25 AM

On my previous layout, I carved foam and covered it with watery-thin plaster to seal it prior to painting. Once dried, you can paint the rockwork using the techniques described by the others. The end result was more than acceptable in my case.

I will soon be doing scenery work on my current layout. I already know at this point that I will be using rock molds. Carving foam is tedious work and I find it difficult to carve anything else than slate. Anyway, that's my two cents worth.

Simon

  • Member since
    February 2008
  • 1,727 posts
Posted by kasskaboose on Thursday, March 11, 2021 11:49 AM

Welcome here!

Painting rocks is somewhat easy.  Paint them black or machine gray with some cheap craft paint.  I make mine out of molds using plaster of paris 

I model western VA and I just paint the foam with two coats of gray paint.  It looks very realistic to what you'd find.  I add the plastic mold rocks for some variety.

  • Member since
    January 2011
  • 817 posts
Posted by PennCentral99 on Thursday, March 11, 2021 11:16 PM

Inspired by Addiction

See more on my YouTube Channel

  • Member since
    September 2003
  • From: Southeast Texas
  • 5,239 posts
Posted by mobilman44 on Friday, March 12, 2021 5:14 AM

Hi!

My first major (11x15) HO layout had a lot of rockwork, mainly to justify an upper level.  I used a lot of rock molds, and as rockwork goes it looked pretty good.  

But I made two mistakes on them (other than having too much rockwork in the first place)............

- I should have colored the plaster when I was preparing it.  This would allow any future chips to not show up as specks of bright white.

- Even though I had read (MR of course) that you should start out with lighter colors when painting rockwork, I knew better.  Ha!  It turns out that the paint ended up being much darker as it dried.  To paraphrase Emeril, it is much easier to amend the colors and go darker, than to go lighter.........

I had that layout for several years (1994-2008) and regreted those dark colors every day.  

ENJOY  !

 

Mobilman44

 

Living in southeast Texas, formerly modeling the "postwar" Santa Fe and Illinois Central 

  • Member since
    December 2020
  • 4 posts
Posted by Toth on Saturday, March 13, 2021 7:28 PM

Hi Everyone - Thanks for the tips and suggestions. I took a scrap piece of foam and tried applying/painting a thin lay of hydrocal over that to see if I can achieve better coloring results by applying washes (the hydrocal is currently setting up).

I think my issue/worry is that the rocks I am creating directly on the foam seem too dark and I'm worried that since my layout has a lot of sheer rock faces/cliffs - my own fault, as I'm limited on space and this is my first ever layout - that eventually the darkness of the rocks will overpower everything. (My strategy for painting rocks directly on foam is to apply a light gray over everything, then with a sponge apply a darker grey and a light brown/tan over about 60%-70% of the rock. Then I apply a wash of black [20 parts water, 1 part black] over everything, and then I dry brush on a few areas of a little burnt umber and green.)

I have yet to paint the tunnel portal in the (attached) picture and since it's stone it should (probably) be some shade of gray. But that gray portal, coupled with the gray-ish rocks, has me worried that the end result is going to be one big gray "blob" - at least in that area of the layout.

I have tried to create lighter colored gray-ish rocks (for instance, applying a 40/1 black wash instead of 20/1) directly on the foam, however, the "rocks" that are created end up appearing fake/unrealistic.

I liked the "rocks" in the pictures I attached in my intial post as they 1) looked realistic (obviously, created by people with far more experience/talent than me! haha), 2) seemed more brown-ish than grey-ish, and 3) were overall lighter than the rocks I'm creating. However, I just can't seem to create rocks that mirror those seen in the pictures from my first post... 

Thanks again!

Image #1

Image #2

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 12,562 posts
Posted by SeeYou190 on Monday, April 12, 2021 9:07 AM

mobilman44
I should have colored the plaster when I was preparing it.  This would allow any future chips to not show up as specks of bright white.

White chips showing up in plaster rock castings is very annoying.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

  • Member since
    January 2009
  • 6,008 posts
Posted by RR_Mel on Monday, April 12, 2021 10:38 AM

Welcome

I like to use Plaster of Paris for my rocks.  I use Woodland Scenics rubber molds for casting the rocks.  I let the castings fully dry then use WS Pigment Stain over the unsealed plaster.  The plaster absorbs the stains nicely.



This is an area on my Red Rock Mountain.



I sealed the rocks with a flat clear coat and about 10 years later I found out that was a mistake.  Over time the florescent lighting faded my scenery and I had to remake my rocks because of the sealer wouldn’t take new stains to liven up the rocks.



The area I model doesn’t have light colored rocks and I kinda like the dark looking rocks.

If you start with light stain you can darken it as you go until it looks right to you.
 

Mel



 
My Model Railroad   
http://melvineperry.blogspot.com/
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 12,562 posts
Posted by SeeYou190 on Monday, April 12, 2021 11:33 AM

RR_Mel
I sealed the rocks with a flat clear coat and about 10 years later I found out that was a mistake.  Over time the florescent lighting faded my scenery and I had to remake my rocks because of the sealer wouldn’t take new stains to liven up the rocks.

Thanks Mel, this is something very good to know.

I have always sealed my rocks with Dullcoat, but never had a layout long enough for fading to become an issue.

My next layout should be for 20+ years, lord willing.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

  • Member since
    January 2009
  • 6,008 posts
Posted by RR_Mel on Monday, April 12, 2021 11:51 AM

Kevin,

I installed fluorescent lighting in our garage for my layout back in 1988.  Over the years it really ate up the color on my layout, I had to replace the flocking three times in 25 years.

I cutover to LED lighting a few years ago and hopefully that put an end to the fading.

The sealing really looked nice for a couple of years but over time the fluorescent lighting took its toll on the color of everything.

Replacing the rocks turned out better than the original so not all bad.  I rearranged several of the rock formations to help make more room for structures.

I’m not taking any chances and I won’t seal my rocks from now on.  The unsealed rock formations still take refreshing stain very good.  
 

Mel



 
My Model Railroad   
http://melvineperry.blogspot.com/
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Users Online

Search the Community

ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!