My fun with rocks

Time for a teaser...

Real rock or plaster casting???

Looks real, good job if you made it.  Tell us how you did it.

Real.

real or plaster cast 

How are you going to apply the rocks?

 

scale rail posted:

Making progress on a huge canyon I'm building. This section goes from six feet to about a foot from the floor and is five feet long. Attached to that will be a canyon from six feet to about 3 inches from the floor and is about twelve feet long. Many of my molds are 3 x 2 feet. I'm making hundreds of pounds of them. This section has a lot of detailing to come. I just spayed most of it with auto primer gray. It will set all night, then the detail will begin. After that a very high trestle will be built across this area. This is by far my biggest mountain project I'v ever tried. It will be the Milwaukee mainline and a electric short line below. It's hard to tell the scale of this but the shot is about four feet wide and three feet high. 

Don

I have a big canyon to build that goes from the floor to the ceiling in the basement.

Any chance you'd share how you made this?? ( Bragdon's molds?)

Here's the rock after three layers of Woodland Scenics latex rubber. Layer three has gauze and so will four. I'll update when I pull the mold off.

aubv posted:

Real.

real or plaster cast 

How are you going to apply the rocks?

Plaster...I think. The moss looks too new for the rock.

I was searching and also found this post with some great stuff:

https://ogrforum.com/t...al-for-casting-rocks

I like the pics on the bottom of the page.

I'm watching all these posts to help figure out how to do it!

AUBV, you're layout and work is fantastic.

Stewart, your rocks look great. How big of an area are you going to do?

Nice work everyone!!!

I bought mold making liquid at Michale's.  I used a cheap paint brush to paint on about five coats.  After each coat I just put the brush in a zip lock bag.  No need to clean it between coatings.I did one a day, but if you use a hair dryer it can go much faster.  After the fifth coating I used mosquito netting which I found at Joe Ann Fabric's.  1/4 of a yard gives you a lot.  I put on the sixth coat and painted the netting and let set.  I added another coat and let it dry over night.  Once the mold was ready I used plaster of Paris I purchased from Home Depot in a 50 lb bag.  I also found a type of hydrocal plaster at a building supply center.  Not a big box store.  The stuff I used dried rock hard in about five minutes.  It cost about the same as one of those milk cartons you get at the hobby shop and goes a lot further.  The best thing to do is make several different molds and pour them all at the same time.  I sprayed my molds with soapy water which help release the plaster.  You can apply your rocks to your wall as soon as it is about set up.  Just hold it in place for a couple minutes until it sets up and peal off the mold.

ChessieFan72 posted:

aubv posted:

Real.

real or plaster cast 

How are you going to apply the rocks?

Plaster...I think. The moss looks too new for the rock.

Engineer-Joe posted:

AUBV, you're layout and work is fantastic. 

Engineer -Joe,

Thank You. You have remarkable powers of observation, making that statement based on a picture of a fake rock. 

It's like ESP! Telepathic powers of perception...... OK, I saw the pics!

..... Nice rock too.

Engineer-Joe posted:

Stewart, your rocks look great. How big of an area are you going to do?

Thank you for the compliment!

The size of the area I will be putting the rocks in is currently unknown. I tore down my latest layout and now plan to build a small layout to practice on. (I will go into detail in my layout thread.) 

Chessiefan,  I poured my first batch of rock molds this week. Your post has been very helpful. Your work looks great and is inspiring.

I pulled the mold off tonight and trimmed the edges. I can't remember if I put on six or seven layers, but the mold feels very durable. Despite washing the rock in the kitchen sink with detergent and warm water before I started, you can see dirt that attached to the mold. The mold separated from the rock easily and looks like it caught all of the detail of the rock.

I made a double batch of hydrocal, only to realize I hadn't added enough of the hydrocal powder to the water as I poured it into the mold. I added in another cup of the powder and mixed it in inside the mold. To add to the excitement, my hydrocal powder was opened almost a year ago and was kept in a plastic bucket with a lid on it. We'll have to wait until tomorrow night to see how disastrous the results will be, lol.

Not being able to fall asleep, I wandered into the kitchen to check on the casting. The casting was firm enough to be removed from the mold and here is the result:

I'll have to shoot some better pictures after work to do this casting justice.

Looks nice.  If you have a flat surface to apply the rock, you can stick it on the surface while it is setting up.  Once the hydrocal starts to harden up, but is still pliable.  Hold it on the surface for a few minutes and peal the mold off the casting.  It should stick to the surface and once dry you can paint it.