A RATHER UNIQUE WAY OF SCRATCH BUILDING HYDROCAL STRUCTURES IN S SCALE

"HAWKEN TIRES & RUBBER" S-SCALE PROJECT IN 24 (NOT SO EASY) STEPS ...WITH PHOTOS

by Philippe Coquet, Paris, France (August 14, 2002)

Edited by Craig S. O'Connell / S Scale Model Railroading Homepage

Since the completion of this project in August 2001, I had promised Craig that I would write a new article, featuring the story of this S scale industrial structure that I fully scratch built over a 4 month time period.

But we all know what it is about: long business days, not enough time for modeling, and at the end of the day, definitely no time available for writing the full story behind a project, especially when, although quite fluent in English, one is not a native speaker.

The good news is that all throughout the project, from early beginning until its completion, I enjoyed the benefit of a new toy - a digital camera - to capture all key steps of the project.

With an array of photos now stored on my hard drive, the idea of writing an article for sharing the techniques with other web-geared modelers was within reach. A couple of quiet business days during the summer of 2002 brought the idea to fruition.

Birth of the project

With so few nice fine-scale modern era structures available on the market in S scale scratch building was the only solution available. This was to be my second S scale display with an urban /suburban flavor, the first being the Big Horn Sheep canyon featured on Craig’s pages since mid 2001.

Due to limited space available in my downtown Paris apartment, the urban display requirements were the same ones as "Big Horn Sheep", ie a 4 ft 9 in. long, 1 foot, 6 inch deep module. In such a small space, some of the structures have to be handled in 2 dimensions, as background walls. A large, bold industrial building was what I was dreaming of, the type of structure so typical of U.S. industrial areas throughout the country.

Overall, I envisioned a rather long building approx. 7 in. high, 1ft 3 in. long, with a depth of 1 in., for closing the left angle of my future display. The good news was that it fit neatly with a sheet of brick embossed paper that I had in my inventory. The brick paper was just good enough for S scale, although a bit over-sized. At that time in 2001, our friend CC Crow had not yet released its fine S scale brick work http://www.cccrow.com/pages/s-scratch-pg.html. The idea of molding the brick pattern into a rubber mold for creating the building was THE right solution. The next evening, the rubber mold (1ft long, 7 in. High, 5/16" deep) was ready ! The project was just beginning !

STEP 1 - Structure overall design

First of all, the overall layout of doors and windows had to be agreed upon. The only commercial parts used for the project were the Grant Line windows & doors (Double Hung windows 30"x72" #4024 and 36" door with 2 windows #4003). Large industrial doors would be modeled with S scale corrugated siding (Builder in Scale) to look like the rolling metal curtains.

Multiple layouts were given a try, and then selected, by displaying the windows & doors on paper.

With so many openings in the walls, I was getting a bit worried by the tedious job ahead: cutting one window after another, then trimming and filing, with undoubtedly less than perfect alignments and a disappointing non prototypical feeling at the end of the day.

While dreaming of this expected recurrent nightmare, a quite interesting idea emerged. Why not create a "counter-mold" featuring all doors and windows into one single "frame", and then pouring the plaster into the rubber mold all around this frame, thus avoiding all of the tedious cut & trim work !!!!!

Let’s give it a try ! Let’s proceed !

STEP 2 - beginning preparations

Once again digging into my 20+ materials inventory, I came up with a real "must have" modeling material called "Forex". This great material is actually Expanded PVC (E-PVC). It is cheaper than conventional styrene, available in thicker formats up to 13/32' approx (10mm in the French metric system), and above all, very easy to cut even when the thickness is above 1/8".

All the "master molds" were crafted with 1/6" thick E-PVC.

The window openings were prepared by gluing 2 layers of E-PVC together. The first layer was fit to exactly the same size as the Grandt Line window openings. The second layer was fit slightly smaller, thus enabling the Grandt Line window frame to be inserted from the back of the wall, in full contact all the way around. The industrial doors were designed the same way.

STEP 3 - quality control !

For each and every one of the windows and doors, special attention was paid to making sure that they were all perfectly square. One single window, if not perfectly square, can ruin the whole project at the first glance. We all know about this.

In the picture of a finished window at left, one can clearly see the 2 layers of E-PVC; the smallest layer being the window masonry opening and the larger one fitting exactly to the size of the Grand Line plastic part.

STEP 4 - floor by floor preparation

Each floor arrangement of windows (or doors for the loading dock level) were then assembled onto another strip of E-PVC, once again making sure that all of them were perfectly aligned.

STEP 5 - final bracing

With all floors finalized, the final step in creating the "master mold" was to assemble all floors together, making sure that all windows / doors were perfectly aligned horizontally and vertically.

2 additional strips of E-PVC were used once again for bracing the whole "structure" vertically into one single solid set.

STEP 6 - Casting preparation - Release Agent

Since I was moving into uncharted waters, I was definitely apprehensive about releasing the frame from the fresh cast Hydrocal. How could I avoid breaking the fresh Hydrocal casting ? Wouldn’t this step require many tries before becoming successful ?

I have not had any positive experience attempting to use release agents in spray cans so I made some trials with Vaseline, which proved quite satisfactory. Thus, I heated Vaseline to make it more liquid, and then brushed the whole E-PVC frame extensively with this strange mixture.

STEP 7 - Hydrocal pouring - Set up

The frame was carefully set into the rubber mold, once again making sure that all verticals and horizontals were square. Note that the bottom of doors are flush with the edge of the rubber mold.

Everything was now set for pouring Hydrocal, which had been prepared as a liquid mixture to avoid air bubbles or gaps as much as possible.

STEP 8 - Hydrocal curing

From the start of the pouring phase, I set some weights on top of the frame, so that no Hydrocal would flow underneath the windows & door blocks.

STEP 9 - Wall casting is Here !!!!

As illustrated by the picture at left, the result was definitely beyond my expectation. Removed from the rubber mold, the building was almost there, with a very thin Hydrocal film covering all openings and no (very few) air bubbles or gaps. The project was in pretty good shape for the time being !!!!

STEP 10 - Separation of the "master mold"

The Vaseline proved its value as I gently moved from one opening to another. The E-PVC openings easily released from the castings. Of course I moved them very carefully, trying not to remove the full window at once so as not to break the fresh casting.

Let’s be fair, out of 2 units done, one of them broke apart, providing this shorter wall on the right.

This "counter-mold’ technique has another very appealing benefit. It makes it very easy to create different patterns in a wall, removing or adding openings by de-bonding windows or doors from the frame (which has been done for the ground floor on the right wall)

One can also notice from the picture of the back of the walls that the frame bracing is visible. However, it does not matter since the interior of the walls are definitely the hidden part of the model.

STEP 11 - Walls assembly & strengthening

Next I trimmed each of the two wall castings making sure that both have exactly the same thickness and that the joints are butt, with the brick lines well aligned from one wall to the other. The two walls have been glued first on a single sheet of cardboard coated foam, prepared with rough cut window openings beforehand, then on some wood beams, strengthening and improving the rigidity of the whole Hydrocal work.

STEP 12 - Walls trimming and "dressing-up"

As illustrated by the previous picture, such a wide and flat wall is not that prototypical and appealing. Of course, the next phase was to "dress up" the walls by adding some vertical and horizontal brick bracing, as in the real life.(Let’s be fair, those were required for masking the wall joint as well).

Strips of brick were cast from the same rubber mold using some Depron strips as separators. Manufactured by Dupont, Depron is another great modeling material that can be found in most Hardware stores in the Insulation Department. It has a glossy finish which makes it impossible to stick to fresh or dry Hydrocal. Having cast the Vertical and Horizontal strips, the next step was to trim them with sandpaper and a fair amount of elbow grease. This makes them all the exact same size and thickness.

Another handy practice worth noting was the use of stripwood dropped into the freshly poured Hydrocal to be used as strengtheners. This actually precludes getting those thin and narrow Hydrocal strips that tend to break afterwards.

STEP 13 - Finished Hydrocal work - Whooo !

With all the bracing done, including the corbel trim (2 strips of brick superposed the smallest one on top of the largest one), the Hydrocal work was …. finally completed !!! The last step before engaging the paint job was to distress a few bricks here and there using a standard hobby knife.

At that time, I thought about pouring the finished piece into the RTV for casting the complete building at once over and over again. However, I was eager to proceed with the project and not terribly keen about starting up my own S scale model structures business.

STEP 14 - Painting and weathering

The paint work took quite a bit of time. Although modeling for 20+ years, and having painted probably 100+ structures over the past decade, I always have problems remembering the precise winning recipe. Reading about new techniques is always very rewarding, but with the years going by ….well the memory could probably use an upgrade ….

For this building, I used the following techniques. First of all, to make the entire structure more homogeneous, I brushed the whole Hydrocal work with white Acrylic Primer. I like using color directly on Hydrocal. However, when some walls have been cast with different plaster mixtures - more or less liquid for instance - the differences in the final paint job become apparent and the final work is not as pleasing.

Then, I used a diluted wash of Oil based Natural Umber and Burnt Umber all over the walls to create a brownish brick appearance. This proved to be quite rewarding. I used rectified turpentine rather than the standard one to guarantee a flat finish when dry.

Then, as described by many specialists (eg CC Crow Clinics web pages), other earth tones were used for highlighting some bricks in a random manner. I used Burnt Sienna, for instance, to create a more reddish shade of brick. Finally, small amount of baking soda was brushed into some of the brick cracks. Finally I airbrushed the walls with a flat finish for fixing the baking Soda.

In retrospect, this is probably the step I am the least happy with. In some magazines, I have seen so many experts at brick wall weathering (i.e Lane Stewart "Facing a blanck wall’ in the Nov.- Dec. Issue of the Gazette), that leave my own skills wanting. However, more fault lies with the manufactured embossed brick paper used as the foundation of the project. Embossed bricks, not having sharp enough angles, prevent the "Baking soda - Mortar’ to stay in between the bricks in a prototypical way.

STEP 15 - Windows & Doors Trimming

With the walls finalized and weathered, I dressed up the windows and doors with top and bottom concrete blocks. This was easily completed by cutting pieces of .035 x .076 (top edge) and .035 x .105 (bottom edge) strip wood, painting them with Polly Scale Aged Concrete, and then gluing them with rapid Epoxy. Once more, alignment is of paramount importance here, and it was worth spending a little extra time for fine tuning the alignment of all the trims.

Finally, another trim was added on top of the bottom horizontal brick strengtheners, using some .050 x .125 strip wood. Door framing was then added using some .100 wood angle (Northeastern), as illustrated by picture on Step 16. Individual windows were airbrushed with Floquil SP Grey, then dry brushed with Polly Scale Aged White. Glazing was added and all windows were glued to the Hydrocal casting from the back of the wall with Rapid Epoxy.

STEP 16 - Concrete Loading dock

Since the building was to face a track siding, a loading dock was required with large industrial doors level with freight cars floors. The foundation of the building was built from 25/32" x 1-1/8" pine girders, then covered with Hydrocal, engraved to craft the joints between concrete blocks, coated with a mixture of Matt medium (Woodland Scenic cement), Ultra Fine grayish ground cover, and Polly Scale Aged Concrete using a paint roller. Finally a wash of Oil based Raw Umber color was brushed throughout the foundation piece highlighting the joints and cracks. When dry, Ultra fine Greyish black chalk was brushed randomly, to highlight the concrete texture.

STEP 17 - Roof dressing-up : Water Tank

The roof mounted water tank is definitely a U.S. industrial architecture landmark. It was a "must have" for this industrial building. For this, I used another commercial product from Plastruct (#16 Utility water tower HO scale), since I was unable to find one fitting my size requirements. As illustrated by the picture, the company name, Hawken Tires & Rubber Co., was designed by using a very common technique using vinyl lettering. Before positioning the lettering onto the tank I painted it with a white-grayish color. The letters were then affixed by spraying them on back with an adhesive. A rust color paint, made by mixing a 50/50 of Floquil Rust and Roof Brown, was then sprayed the whole tank with the final color.

STEP 18 - Roof dressing-up : Water Tank structure

The base of the water tank has been freely designed, with references from some pictures I researched, and executed using Evergreen various styrene stips, mostly L shape girders (1/8" and 3/32" angles from Evergreen). Ladders have been fully scratch built, but are, in retrospect, oversized for S scale. They will be replaced, in the future with much more realistic metal grab irons (using S scale 18" straight style Grab irons available from CMR)

STEP 19 - Roof dressing-ip : Air conditioner

The Industrial Air conditioner is another commercial part I decided to use, although designed for HO scale. It is available from Walthers (# 3157 Corner-store series - Roof air conditioners) The kit offers multiple sizes of air conditioners. The largest models are well proportioned for S scale. The air pipes were crafted using rectangular tubing (Evergreen #259 .250 x .355).

STEPS 20 & 24 - Enjoying the work completed

Finally, the scratch building project came to its end, almost 4 months after its inception.

For those of you who may wish to launch such a project, a word of caution. It took so damned long to complete. I really stopped counting the hours. However, I am quite proud of the finished product...perhaps some motivation for having spent some extra hours writing the article you are reading at the moment. And finally, as we all know very well, the hobby is about having fun. It is about trying and testing new techniques and, yes, it is also about failing sometimes too. Ultimately it is always about having created something from one’s own hands that one can be proud of !

STEP 25

Now the story is not over. Perhaps next year I will share with you another article about creating my second S scale - urban - display (still unnamed). For the time being, here is the work in progress, including at the far left, the Hawken Tires & Rubber building.

One of the very new and very neat features of this new display-diorama being the customized background image, which was designed with Photoshop software by one of my French fellow (a great modeler of HO scale US prototype - Jean Luc Collard, and also a pro of digital image editing) . More to come soon !