Printer Friendly Version

Painting Plaster Kits
By: Grant Knowles

The Ed Fulasz Corner gase Station as built by Grant Knowles for Don Leger. It has been named after the late Howard Scodras.

Part Preparation

In the previous step; Preparing The Castings, we delved into the key steps of cleaning up the plaster castings and ensuring the parts fit together tightly. Before you rush into the painting phase, go back and double check your preparation work as it will become increasingly difficult to fix any errors as the structure comes together. Look for any unsightly gaps, ill fitting pieces and any surface blemishes that will need to be filled / removed.
When you are confident all is in order, then it's time to start the painting process.

"Staining" vs. "Painting"

There are two distinct methods for colouring plaster castings: Each has their distinct benefits and approach. The "staining" approach leverages the porous surface of the plaster to "soak" up any thinned paint much like you would experience when staining a fence. The benefit here is you can apply the stain in repeated layers until you obtain the desired colour density. Also, should the plaster chip, the white of the plaster will not show as the colour has penetrated below the plaster surface.

Sealing on the other hand plays on the concept that the surface of the plaster is sealed so that it can be painted as per the normal processes one would use for plastic type surfaces.

Both approaches work very well, so try each to determine which method yeilds the results you are looking for.

Note - this page covers the Staining Approach while the next section (by Chris Lyon) covers the Sealing approach.

Stone Wall - “Staining” Approach - Mineral Based

The first approach we will cover here is that of staining a stone wall casting to make it look like real stones. In this case we will be using the Floquil brand of mineral based colours and wood stains.

Step 1
First step is to add a light beige back ground colour to the casting. Open up a jar of a light colour such as Earth or Foundation. Then take your paint brush and dip it into a jar of paint solvement then into the paint jar (make sure it has been thoroughly mixed first). Then apply this soupy mixture to the plaster casting. Repeat this process to cover the full surface. Make sure there are no white plaster showing through.

Apply the base colour stain by first dipping the paint brush in the solvent then into the paint.

Step 2
Next step is to “stain” the individual stones different colours.
Collect your jars of stains and thoroughly mix them up. Choose stain colours that will reflect the type of stones used on the structure. The colours I have used include: maple, oak, driftwood, teak, cherry, etc.

A collection of Floquil stains used in this example.

Take your first jar of stain, grab a fine tipped paint brush and start "dabbing" the stain on individual stones. Do this in a random pattern making your way across the plaster casting. Repeat this process for each of the remaining stains. You do not have to stain all the stones, leave some with the background beige colour.

Here is the casting after random stones have been coloured.

Here is the fun part. We'll now paint over the whole casting with some very diluted indian ink.
If you haven't already got some on hand, take a small jar of rubbing alcohol and add a few drops of indian ink. The idea is to create a weak inky mixture that can be applied to the stone wall to tone down the surface colours. You may need to experiment with your Indian Ink / Alcohol mixture to get a colour density that works for you. Remember it's always easier to darken the surface with repeated applications, it's next to impossible to lighten up a colour, so error on the side of caution.

For comparison purposes, the right side has been stained with black Indian Ink while the right side has been treated with brown. A significant difference between the two!

Here is a wall that has been stained by the process outlined above.

Stone Wall - “Staining” Approach - Acrylics Based

Another approach to take that is less dangerous on the lungs and nose, is to use acrylic paints instead of mineral based paints. You have all seen these in the craft stores under such names as Ceramcoat and Apple Barrel.

Step 1

As with the previous process, the first step is to "stain" the bare casting with a beige coloured paint. Dilute the paint with water to arrive at a loose stain mixture. Apply this to the whole casting.

Step 2
The next step in the process is to spot stain the sones with different shades of colour. In this case, I chose to stick to a grey theme and found a number to acrylic paint jars in my collection that filled the ticket.

Here is the stone wall with the individual stones coloured. Note some stones were left the beige back ground colour.

Step 3

The final step is to apply a coat of diluted Indian Ink to tone down the stone colours and blend them all together.

Brick Wall - “Staining” Approach - Mineral Based

We will follow a similar approach to "stain" colour a brick wall.

Here is the brick wall that we will be colouring in it's true naked colour!

Step 1

I chose to use Reefer Orange as the base colour to replicate the brick colour found on turn-of-the-century buildings.
Once again, we want to stain the casting, not paint it so dip your paint brush in the solvent first then into the paint. Slop this onto the full surface of the casting, do not leave any white spots.

Step 2

Next we will spot stain a few bricks darker and lighter colours.
Often the colour variant in a wall is a result of different firing and aging of the bricsk. To replicate this, take some brick colour paint and add a drop or two of black or dark brown. Mix this up and apply following the staining approach. Colour individual bricks at random with the mixture. Just a few as this is to add a little variation to the surface.
Lighter colour bricks can also be done this. In this case, start with some white paint and add a few drops of the brick colour until you arrive at the desired shade. Apply this to the wall in a random staining fashion.

A few individual bricks have been touched up with a darker brick colour.

Note, as this wall contains two briced over windows, we took this opportunity to brush paint the old window sills. Here we used full strength paint.

Step 2

It is now time to add the mortar colour
To do this we selected a water based paint colour that replicated the desired mortar colour, in this case, a light grey.
Dilute this colour a fair bit then slop it all over the brick wall making sure asll the mortar lines have been coloured.
Let this dry for a few minutes then gentle wipe the excess off from the top of the bricks with a paper towel.

Slop the diluted mortar colour over the brick wall and allow to dry for a few minutes.

Now gently wipe off the excess mortar colour from on top of the bricks. Experiment here to find out how much mortar you want to leave behind for the over all effect. You can always add more mortar colour if it's too thin.

Step 3

As a final weathering" you can apply a layer of diluted Indian Ink.

A very dilute wash of Indian Ink was used to tone down the brightness of the wall.
Notice how leaving some extra mortar colour in the corners helps to emphasise the different "layers" on the wall.

Brick Wall - “Staining” Approach - Acrylics Based

I chose to experiment with a different approach on the brick wall when I used the water based paints.

Once again, locate your collection of acrylic paints as we will need them for this stage.

Step 1

Let's apply mortar colour first.
Locate the paint colour you want to use for the mortar. Create a diluted mixure (about 50 / 50) with water and stain the full wall panel.

Here part of the wall has been "stained" with the mortar colour.

The fully primed wall.
Though I had painted the concrete sill at this point, I would recommend doing this later in the process.

Step 2

Now it's time to "dry brush" the brick colour on.
Dry Brushing involves picking up paint on the paint brush then wiping most of it off before painting the casting. Following this approach will ensure the paint only sticks to the high surfaces and does not flow into the cracks. The cracks in this case are the mortar lines between the bricks.
Colour variation in the bricks can also be done at this stage by tinting the base colour and spot painting selected bricks.

The paint brush is first loaded up with some paint, then whiped on the paper towel to remove most of the paint the carefully brushed over the top surface of the bricks.
The paint then only sticks to the surface of the bricks and does not flow down into the gaps between the bricks.

Step 3

The final step would involve applying a diluted indian ink wash.

The finished product.
My brush streaks are a little more visible than I would have liked, so next time I use the appraoch, I think I will mix up my brick collur in advance then paint the wall thus ensurign the colour density is consistent. Other than that, I'm pleased with the results.

Wrap Up

As you have probably realised, there are many differnt ways to "stain" plaster castings. You will need to experiment with these to find the approach you are most comfortable with and the one that yeilds the results you are looking for.

This Web page is maintained by Grant Knowles and was last updated on Dec 26, 2009.