Once the original blueprints were scanned at 400 DPI by Draftech, we experimented to find the best way to convert them back into positives, better to view them as originally drawn by architect Brainerd Jones. With Candice's extensive knowledge of image processing theory, we developed a seven step Photoshop "recipe" to filter and enhance the images. The results can be downloaded from the blueprints page of our regular website.
All blueprints are unique, but we believe these directions yielded the best possible results for our data. Despeckling twice, for example, removed just the right amount of "dirt" from the image without harming significant fine details in these drawings, including evidence of erasures. Your mileage may vary; only by experimenting with the settings on your own blueprints can you find the optimal tweaks. (We urge you to follow the exact sequence indicated below, however.) The final step -- reducing the image down to 200 DPI -- is optional, but practical; it makes a great difference in the file size with no appreciable degradation of quality.
Each step includes the menu path where that particular tool can be found in the Mac OS X version of Photoshop 7. (This post has nothing to do with old house restoration, of course, but we didn't have a better place for this topic, which is certainly "obscura.")
ERRATUM, APR. 26: a typo in the custom filter was fixed.
Custom filter: | ||||
0 | 0 | -1 | 0 | 0 |
0 | 1 | 1 | 1 | 0 |
-1 | 1 | 8 | 1 | -1 |
0 | 1 | 1 | 1 | 0 |
0 | 0 | -1 | 0 | 0 |
scale 8 | ||||
2) invert (Image > Adjustments > Invert)
3) apply custom filter shown at right (Filter > Other > Custom)
4) set levels 0 1.55 155 (Image > Adjustments > Levels)
5) despeckle twice (Filter > Noise > Despeckle)
6) set threshold to 237 (Image > Adjustments > Threshold)
7 optional) set to 200 DPI (Image > Image Size)
As noted earlier, no wood was supposed to be painted, inside or out, but there's at least two coats on the exterior trim. We'll strip that paint, of course, but what should replace it? What color would 100 year-old redwood be? I actually pondered this question for a couple of days before realizing that we had a house filled with examples.
But the question still wasn't easily resolved. The interior redwood trim varies greatly, from a rich brown to medium tan, some with yellow tones of old pine and some as red as cherry. Sunning can be blamed for fading in a few situations, but not all; this issue and its remedy needs further study. So we're back to a variant on the original question: What color SHOULD 100 year-old redwood be?
To experiment, I took a sill from a basement vent that was badly rotted underneath and needed
to be completely replaced (shown to the right, just for reference sake). Stripped of the remaining paint and thoroughly sanded down, the old redwood on the top of the sill had a color that might be called "Martian Sand."
Jones' specifications required that "one good coat of Pure Boiled Linseed Oil" should be applied first. The 1905 carpenters were working with fresh redwood, of course, which had a different nature than what remains now a hundred years later. To test how linseed oil would interact with the old wood, four test areas were sectioned with painter's tape dividing them, following with the application of 1, 2, 3, and 4 coats of oil as shown below, left to right. (Some of the linseed oil leaked under the painter's tape, but the test areas are still distinct.)
With a third and fourth coat of linseed oil, the wood became darker and more of the red color
came out, as seen in this closeup of the wood with 4 coats.
I also used this opportunity to test the waterproofing ability of linseed oil, placing a drop of water on each test strip and on the bare wood. On the untreated surface the water was absorbed almost immediately, within 15 seconds. The beads retained their shape for 30 minutes on the 1-coat strip, and for 50 minutes on the 2-coat strip. For both the 3 and 4 coat sections it took about 70 minutes for the drops to disappear. Conclusion: Linseed oil is a terrific weather protector, but there are no real advantages to using more than two coats.
The final part of Brainerd Jones' instructions were to apply a second coat of linseed oil, mixed 2:1 with turpentine, once the wood was in place. This is an old formula for furniture polish that may date back to the 18th century; variations appear in many Victorian texts, sometimes using a 2:1:1 mix of linseed oil with turpentine and vinegar, the latter as a cleaning agent.
Below is a photo of the sample wood with a 2:1 mixture rubbed the entire width, with no effort made to restrict the application to the sample strips.
The turpentine/linseed oil formula makes a dramatic change. Much more red is immediately
apparent, as shown in this closeup of the section with 2 coats of linseed oil.
The color is also far more uniform, split between just the two shades of deep red and dark brown. The lighter brown tones seen in all the oil-only tests are gone.
While this 2-coat oil/turpentine test results in a slightly darker color than the single coat of linseed oil specified by the architect, it makes up for it in the dramatic boost in red tones. Overall, we believe this must be what the exterior wood would have looked like if it'd been kept in original condition since 1905.