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Brick Wall Decals |
Computer "magic" turns a prototype photo into a realistic structure
by John Nehrich
We had been struggling with the challenge of making realistic brick buildings for our HO New England, Berkshire & Western club layout here at the Rensselaer Polytechnic Institute. Long ago we had mastered a practical method to scratchbuild brick buildings using styrene and Holgate & Reynolds embossed brick. Although they were complete, detailed scale replicas, the finished structures often seemed to fall short of their prototypes.
The main reason was color. On a real building, brick walls display a myriad of colors and patterns, which is difficult to capture on a model. We tried all of the usual techniques for coloring brick, but none provided the realism we were looking for.
The answer came by combining prototype photos with the ability to scan images into a computer, alter and correct the images with software, and then being able to print the resulting image onto plain decal paper. The idea of doing this for signs isn’t new, but we took it a step further by decaling the entire side of a building.
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The system
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Use a sharp hobby knife to cut the decals slightly larger than the surface to be covered.
Lou Sassi
| | We began figuring this out when we got a new computer with a color printer and scanner. Using Adobe Photoshop software we could scan in a photo of the side of a brick building, square the image by removing perspective distortions, eliminate unwanted foreground elements such as telephone poles or parked cars, and scale the image to the proper size. The resulting color printouts were great for use in the background, but lacked the three-dimensional relief needed for foreground use.
The solution came when we took the plunge and got an Alps printer, which allows printing in white. By printing our images on clear decal paper, the resulting decal could be applied to the entire side of an embossed-brick model. Decal setting solution blends the decals down into the mortar lines, resulting in extremely realistic surfaces. We soon began applying decals to every wall surface we could.
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The image
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Slide the decal partially off the backing paper and maneuver the decal into position, then slide the backing paper from underneath the decal.
Lou Sassi
| | It’s important to try and match the period of the building you’re modeling to the image. If possible, use a photo of the actual building you are modeling. Keep a camera handy, and keep an eye out for interesting walls and structures.
Patterns of weathering on a wall – much like freight cars – are truly unique. If you use the same image again and again it becomes recognizable. Because of this we use a different photo for almost every wall.
Full-blown Adobe Photoshop is expensive and takes a powerful computer. There are many other less expensive image-manipulation software packages that will work, but be aware that some don’t allow you to skew an image to correct the perspective. If you don’t have a scanner or photo manipulation software you can go to our Web site (www.union.rpi.edu/railroad) and download some of the images that we’ve used.
When sizing an image I’m usually not sure of the exact scale, but I find if I get it close to 11 bricks to the inch across and 19 bricks to the inch high, it will closely match the H&R material. A lot of commercial kits have oversized bricks, but for this technique to work you only have to be in the ballpark of the model brick size – a perfect match isn’t necessary.
We’ve also made decals for wood and concrete block structures. We applied a decal to the flat-faced Holgate & Reynolds block material, and the effect is pretty convincing. There was some misalignment between the mortar lines on the decal and the embossed vinyl, but even on close inspection the effect still works.
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Signs
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If you need to move the entire decal, add water liberally and use a soft brush to avoid tearing. Once the decal is in position, add a setting solution such as Walthers Solvaset.
Lou Sassi
| | One of the nice features of the computer decal technique is the ease of adding signs painted on walls. The old technique of sanding down a printed paper sign and then gluing it to the wall using diluted white glue is now as obsolete as the horn-hook coupler. You can now take photos of real painted-brick signs, complete with the most realistic weathering.
By using the scanner and computer you can also take ads from period city directories, magazines, books, or most any other source, colorize them, and digitally paste them onto a brick wall image. You can even cyber-weather them so they look faded and streaked. Lettering can easily be made to fit the available space, with the alignment done by the computer, rather than trying to get the spacing and alignment correct with individual dry transfers.
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Making the decal
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The tricky part of this technique is getting the overall color and brightness to blend with the rest of the layout. You can use the computer to adjust the color balance, brightness, and contrast of the image, but what you get on the screen might not exactly match what appears on the decal. If you start to place the decal on the building and it just doesn’t look right, don’t be afraid to peel it off, go back to the computer, and try again.
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Micro-Mark makes a special decal paper and fixative for printing decals from an inkjet or laser printer. If you don’t have access to a printer, many copy centers will photocopy material for you onto decal paper. Only the Alps printers can print white, so if you’re using a standard laser or inkjet printer you’ll have to use a white decal sheet, not clear.
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Applying the decals
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Before the decal sets, use a sharp hobby knife to trim the decal from the windows, doors, and other details. Use tweezers to remove scraps.
Lou Sassi
| | Working with large decals is a little different from the tiny pieces you might be familiar with for decaling rolling stock.
Cut the decal to the basic shape of the wall, but slightly larger than needed. Soak it in water long enough for it to loosen, but not long enough to float it off the backing paper. The backing is important to transfer the delicate film to the model.
Hold the decal against the wall and start to slide it off the paper. Align one corner and then, holding down that corner with a finger, slide the paper out from underneath. If the decal winds up in the wrong place, soaking the surface with water will allow you to shift the decal.
We generally apply the decals to finished buildings, decaling right over the windows, doors, shutters, and other details. The trick is to first paint the wall a color that’s close to the shade of the decal. That way if a bit of the wall is exposed, it isn’t noticeable.
Add setting solution. As the decal begins to settle, the details emerge in bas-relief. Using a sharp knife it’s easy to cut the decal away from details and peel it off.
Don’t wait too long to cut away the excess, or the setting solution will have made the decal adhere to the surface. If that happens you’ll have to scrape away the decal and probably do some paint touch-up. On a wall with many windows and details it’s a good idea to apply the setting solution to only a small area at a time, then remove any pieces of decal necessary before moving on to another section.
At first the decal film cuts like onion skin, which requires slicing with a sharp knife. As the setting solution starts to do its work, the film becomes more like wet tissue paper. Use the knife by pushing down and parting, rather than dragging.
Repeated applications of setting solution will cause the decal to settle even more, revealing the relief of the mortar lines. On foreground buildings I run the knife along all the horizontal mortar lines. This goes quickly, as you can let the knife find its path as it runs along each groove.
Adding an overspray of flat finish on a completed building does frost the windows, but frankly that’s an effect we like. I suppose we should overspray every decaled wall, but in truth often we don’t.
On some walls where the decal color is off, or too light or dark, I use a thin wash of Delta Ceramcoat Bambi Brown, a soft fawn or salmon water-based craft paint, to tone it down and blend it into the overall scene.
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Other possibilities
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You can see the dramatic improvement between the painted building in this photo and fully decaled structure in the larger view. Click on the photo to see the larger view.
| | One annoying (in a good way) problem is that the “wall of decal” effect is so good it’s almost like painting something in camouflage – it sort of disappears, guiding your attention to the next wall, which suddenly becomes too stark and plain.
This technique has possibilities in several other areas. One variation I’ve been pondering is using this technique on rolling stock to capture all the interesting nuances of prototype weathering. Because the decal film is so thin, I plan on printing decals of HO clothes, down to polka-dots and stripes, and hanging them on a clothesline. They should wrinkle very realistically. Other possibilities include a multi-striped awning, which would sag like its real counterparts, or a patterned table cloth on a picnic table.
On a more ambitious scale, we are planning on modeling the Delaware & Hudson’s stone station at Port Henry, which has rough hewn stone and massive arches over some of the openings.
I want to copy this stone by stone, so I plan to make a scale decal of each wall from a photo, apply each decal onto a blank slab of plaster to serve as a guide, and carve the blocks following the lines. Once the lines are carved a second decal will provide the coloring.
I’m heading back to the workbench to try out a few of these ideas. You’re invited to do the same, and let your imagination guide you.
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the copyright of Kalmbach
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