Here is the method I stuimbled upon while mixing everything imaginable together in search of an easy and very realistic brick finish.
There are other methods that use some of the products listed below but as far as I know I'm the first person to use them all together.
This method won't work on styrene or hydrocal.
Here is what you need as shown from left to right.
Baking Soda.
Fiebing's Black leather Dye.
Letraset TRIA Art Marke color # Pantone 180.
Denatured Alcohol.
Testors Dull Coat.
Trigger operated spray bottle.
Quickrete Anchoring Cement.
I stronly recommend Feibing's BLACK leather dye for this. Their black is actually a bluish black that works much better than a solid black (USMC black) for this method of brick coloring. There are other leather dyes out there besides Fiebing's but as far as I know they are all solid black such as the shoe dye from KIWI. This is too black and ruins the whole process. Fiebing's BLACK leather dye can be purchased here http://www.aleathersource.com/Dyes.htm
Make an alcohol/leather dye mix in the spray bottle by combining 16 parts alcohol to 1 part black Fiebing's leather dye. This absolutely has to be made with DENATURED alcohol which is available at hardware and paint stores. Isopropyl/rubbing alcohol will not work so don't even bother trying it. Only denatured alcohol will cut through and mix with the alcohol based magic marker and leave a very convincing brick coloring. The picture below shows a casting that has been colored with the Letraset TRIA art marker (Pantone 180). Other Pantone colors such as #484 also work well for brick coloring. #484 is a reddish color that when combined with the alcohol/leather dye mix creates varied reddish brown bricks. I've tried other brands of markers but they don't work well for this purpose.
Letraset TRIA art markers are sold in art stores and online.http://www.letraset.com/us/info/products/Tria-Markers.asp
Let me make it perfectly clear that this method will work as described only with the exact products listed above. Use of any other markers dyes or alcohol could result in disaster so use them only at your own risk. I have tried some other markers and they didn't work but there may be some out there that will. If you end up with bad results there is nothing left to do but break out the paint and paint it like a plastic model.
Step One. Color the entire casting with the marker sure to get inside window and door openings. You will need to go over the casting a couple two or three times to get even coverage. Let this set for a few a while until dry. After drying the casting may still be shiney and a little sticky but will be taken care of in the next step.
Step two. Adjust the spray bottle nozzle so it's just barely on mist (slightly blotchy mist). You want to lay the casting on a flat surface and let the spray rain down on it. Pull the trigger slowly as you sweep over the casting. You'll need to go over it 2 to 6 times depending on how washed out and old you want the bricks to look. I went over the casting in the photo below 5 times. Notice the randomness on the bricks and blotchy pattern the dye left on the white cardboard I set the casting on. Let this dry completely. Spray the casting with Dull Coat and let that dry.
Step three. Use a soft brush and cover the casting with Quickcrete Anchoring Cement. There are other hydraulic cements out there but I've found the others I've tried to be too dark. Use a very slightly damp paper towel or rag to wipe the cement off the face of the castings. Follow this with a light spray of Dull Coat to seal it. Repeat the Quickcrete application again if necessary. It's often eaier to apply the mortar to the arches in a seperately once the rest of the wall is done. A final step would be to use a little baking soda between the bricks in random areas and sealing it with Dull Coat. Sprinkling the baking soda on to the bricks and then blowing on the casting can create a random effect. You can also rub some in here and there with your finger where ever you really want it to stand out. Any stone parts of the casting are painted after.
This technique gives very random results and you never know exactly what colors
you're going to get but it always looks good.
The bricks in the photo below were done with Pantone 180 marker,the Bblue/black ink mix and the hydraulic cement mortar. I let the marker dry overnight and then went heavy with the ink spray. I didn't bother with the baking soda on this one after seeing how the other steps turned out.
