Coloring Hydrocal Rock Castings

[Allegheny2-6-6-6]

Phoebe Vet

It sounds like a good system on the surface, but I have a question.

How do you determine what the final color will be when you are adding the paint during the mixing?  It's not something that can be adjusted after the fact.

 

 

Well powdered tempra paint is just that a dry powder, so what he did was mix in the black until he got the grayish color he was looking for. Did the finished color come out exactly as the color he anticipated it would I can't say for certain but one this is that if any of the hydrocal or plaster gets chipped or cracks a little you don't see the great white void as the (gray in this case ) color is mixed through out the mix. So as he explained it to me if you were to break off a chunk and crumble it there would be gray powder instaed of white. Nothing new and innovative plasters have been doing it to wall in houses for years.

Here is a link to a site that lists a whole bunch of colors used to die concrete etc. so why can't it be mixed into hydrocal or plaster? For the price of a sample kit I think I'll be willing to experment a bit.

 

http://directcolors.com/ConcreteStain/Concrete_Pigment.htm?gclid=CP70oPrjipkCFQETGgodWkqhlw

[Don Z]

I have a 2 pound bag of red dye that was used in the mortar when the brick was applied to our home. A local company, Materials Products International sells the product. Here's a link to their 'bagged goods' page of their website. They have many colors listed. You might find something similar in your area.

http://www.mpi-austin.com/catalog.php?cat=2

Don Z.

[Phoebe Vet]

Bob:

Where does one find these "dye coloring products" and which ones do you recommend?

[bogp40]

Phoebe Vet

It sounds like a good system on the surface, but I have a question.

How do you determine what the final color will be when you are adding the paint during the mixing?  It's not something that can be adjusted after the fact.

This can be a problem with any wet agent added to plaster. The coloring is only a base to be further stained, painted etc.

Many will find that any pre coloring is not nec..The reason I do color the castings is to stop any of the white chipping to show. This is done for a club enviorment where some abuse and handling may occur.

I have experienced curing issues when adding paints and even other liquid products to Hydrocal and veneering plasters. This may not be too much of a problem, but using a dry dye formulated for masonry products just works so well. The dye coloring added to the dry product is very close to the final dried, cured look.

I have also found that to produce very dark coloring using paints, that a considerable amount of the coloring is nec. The dye can almost give a black or dark brown to the plaster w/o needing a large amount.

[Phoebe Vet]

It sounds like a good system on the surface, but I have a question.

How do you determine what the final color will be when you are adding the paint during the mixing?  It's not something that can be adjusted after the fact.

[Allegheny2-6-6-6]

Haven't tried it yet so I don't know how well it works but I have a friend who colors his hydrocal, plaster etc. with powdered tempra paint while he's mixing it. I've seen on his layout where he has some fairly large rock formation where he mixed black & white tempra in with the hydrocal to give it a gray coloring. After the hydrocal had dried he went back over the whole formation with India ink and alcohol looked pretty darned convincing.

[bogp40]

Jarrell, To add to Don's installation of the partly set mold, If you feel that you may need a better bond, mix a small fresh batch of plaster to butter the casting. I had a few castings that didn't quite bond as well as I wanted. This provided an extremely strong bond, even on pink foam.

[Don Z]

Jarrell,

If the previously applied casting is completely dry, then yes, we did wet it down before applying the new casting.

Check your email....

Don Z.

[jacon12]

 Don, when using the technique of placing the 'wet' (still in a pudding state) casting on the layout as you've described, does it matter if the rock that is already there that the 'wet' one is going to be against is already dry or not?  I'm guessing you may have to spray the dry casting with water when placing the next one against it.

Thanks for the picture!

Jarrell

[HHPATH56]

 Hi, one and all,                                                                                                                                   For one area of "hard knocks" on the scenery at the head of the entry stairs, on my layout, I used concrete patch, instead of Hydrocal. Perhaps, Hydrocal would have withstood rough handling just as well. Someone mentioned the use of masonry coloring added to the Hydrocal mix.  I like to do the same, since it negates the white powder from drill holes that occur when drilling holes, to "plant" hundreds of tree on a hillside made of white Hydrocal plaster.          Bob Hahn

[Phoebe Vet]

I let the castings dry for about 24 hours and then use a very diluted wash of paint.

This is not quite done, Ithere is more to add below the rocks.

 

[Don Z]

Jarrell,

Sorry for the delay in responding. I had typed out my response last night and was just about ready to hit 'Post' when my video card died and took down my system....so, here we go again.

The castings you see in my photo are made from several different latex molds. The plaster is allowed to sit in the mold until it is about as thick as pudding, then the mold is lifted and applied to the hillside. The plaster is wet enough to adhere to the terrain, wet enough to conform to the terrain, but dry enough so it won't run out of the mold. The mold remains on the casting for about 3 minutes and is then removed.

The castings are overlapped, eliminating the need for 'filling in' with Sculptamold or plaster. After the castings have cured for about an hour, a chisel is used to 'pop off' sections of the castings that overlap in order to blend the two molds together. The plaster dried for at least a week before any color washes were applied.

I had the huge benefit of having the guidance of the modeler that created this scene at my side, guiding my every step in learning the process:

He also made his own molds that were used on my layout. The band of red rock at the base of the hill is one mold that is 3 feet long. It was flipped end to end to hide the repeat in the pattern. Let me know if you need any more information.

Thanks,

Don Z.

[jacon12]

 Wow... I see I need to go back to rock making 101, you guys are doing some beautiful work.  Don, I do have a question about your rocks.  Are those many castings bunched up close together and if so, do you also use hydocal sculpted in between the castings?

Thanks all for the pictures!

Jarrell

[MAbruce]

I've been working on this lately.  First, I let the plaster dry.  Then I use thin washes using acrylic water base paints (sprayed on).  It takes several passes before the colors set in deep enough.  I then seal it with a clear Matte sealer spray-paint.

 Here's the latest rock wall on my layout (no trees, bushes, or ground cover added yet):

 

 

 

[nbrodar]

 I wait until the castings are completely cured and installed before I start the coloring process. 

I start with a dark gray stain

Followed by drybrushes of browns, tans and grays

Until I get the desired look

 

Nick

[MisterBeasley]

This is the back yard of the old mill.  The rock wall castings are from a Dave Frary mold.  I used a rattle-can of Rustoleum speckled brown spray paint for these.  I think the speckled texture adds a very realistic coloring to the casting.  After that, I used a thin wash of India Ink (in water, I think, but maybe alcohol) to add highlights.

I just did this casting with straight white Hydrocal, no pre-coloring.  Because I'm using spray paint, I usually fit the piece on the layout, and then take it outside to paint it.

I haven't tried the speckled paint on a natural rock face, but I think that would look pretty good, too.

[bogp40]

Don,  Excellent rock work and coloring.

[bogp40]

Jarrell. Any of the castings done for the club layout are always dyed to a base color. I use powdered masonry dyes for this. The dye is added to the dry plaster/ Hydrocal before mixing. If you add the dye to wet plaster you have no idea as to the dried, cured color. This is much like tile grout in that a light gray will look black when wet. The dyes are found at building and masonry suppliers and comes on a variety of colors. The most common colors are black, brown and red brick. 90% of the castings will be some form/ mix of the black and brown combination. This dyed plaster is done for stone, concrete and even roads. Many times the dried plaster only needs minor staining and coloring to acheive the desired effect. These concrete abutment castings where dyed to the grey shown. A simple form was made and they were cut and fit. Finished area, w/ staining and weathering of the castings Production molds , the main color shown is the dye. Additional coloring/ weathering done once the castings are set and dried. The pilaster shown was done the same. The stone was made from a simple pour w/ a foam texture base, dried panels were scored and ripped into strips. These were then glued to a tapered wood form. The use of masonry dyes doesn't affect the properties of any plaster as some of the liquid or a paint can do. It's just a bit of experimenting w/ the colors. Others may only paint the white castings and go from there, but the dyed plaster works well especially in a club envioronment where mishandling will show those awful white chips that will have to be touched up.

[Don Z]

Jarrell,

I always wait until my plaster is dried and cured before applying any color. I use thin washes of paint to color the castings and I'm pleased with the results. Since you asked for a photo:

Don Z.

[jacon12]

 I've experimented with different ways/methods of coloring or staining hydrocal rock casting with various results.  Tell me, how do you like to do this.  Do you let the rock completely dry, after it's installed on your layout, or do you prefer to apply stain/paint while it is still damp?  Do you prefer a thin stain or do you cover the casting with paint?  Would really like to hear your method and, if possible, see some pictures if you have them.

Thanks,

Jarrell