Beacon Hill Tower Roof (Step 3) Verdigris Tests

Here are the results of the first round of testing finishing techniques for the copper roofing material. The raw copper sheeting is way too shiny. A darker shade of copper, like the oxidation that occurs naturally -- think the brownish look of older copper pipes -- would be much better, as well as the introduction of some of the green verdigris, which forms in humid climates. [Fun fact: research revealed that Verdigris isn't just a color change; it is a compound formed on the surface of the copper and can be scraped off. The resulting powder can be mixed with oils to form a unique shade of blue-green that some artists use in painting.]

Two aging methods were used in the first test session. The first uses a half-and-half mix of salt and white vinegar. Several web sites suggested using non-iodized salt and some suggested adding ammonia, but I didn't have either one on hand, and not wanting to venture out into the sauna that is New Orleans in the summer, I used what I had. The second method tested uses Tabasco sauce. Every New Orleans kitchen has a supply of Tabasco sauce.

Yet another website recommended urine for aging, but that is so not going to happen.

Here's a photo of the overnight test lab. Humidity was recommended as a way to enhance the process, so a twist of paper toweling in water was included under the tent, which is a piece of plastic grocery bag. The Tabasco test at upper left was not tented. A relatively big puddle formed and I figured it would take all night to evaporate; I was right. (Click the pictures for a closer view.)

Below is the original test piece, which was first wiped down with a bit of window cleaner with ammonia to remove any oils that would interfere with the aging process.The section to the right was painted with the salt/vinegar mix. The first application dried rather quickly. It received another coat before installing the plastic tent. The result: it has formed a few grains of verdigris, but mainly turned the copper surface dull and pinkish. I'm not loving the look, but I'll keep an eye on it to see if there are further changes as it dries.

A member of the Greenleaf Dollhouse Forum suggested I soak a piece of paper toweling in the salt/vinegar mix and leave it on the copper to see what would happen. When I took it off this morning, some of the verdigris stayed on the copper, but much of it pulled away, having soaked into the toweling. Maybe if the toweling were not quite as wet, more would stick to the copper? This needs more experimentation.

Here is the most intriguing test result: the Tabasco sauce. The right side shows the lovely deep green verdigris that formed. It is relatively thick, as thick as the original puddle. As far as I can tell, the copper turned the sauce green. The oval fingerprint shape is where I touched it. That bit was still wet and it pulled away very easily. Where the edges are dry, the verdigris clings very well. The left side of the test piece was lightly coated with sauce on a cotton swab. It has darkened somewhat without turning green. The bit in the middle is the untested copper. 

Of the tests done so far, I'm leaning toward the Tabasco sauce. It is mainly vinegar and salt with hot peppers, so why wouldn't it work? Used sparingly, it can take the edge off of the shininess, and used more heavily along the seams, in corners, etc., it will turn that lovely green color. And once dry, it clings very well, so I can lay the panels flat to age them and let gravity do the puddling. Will the left side continue to darken? Only time will tell.

The plan is to let all of these tests age for a while to see if there are additional changes. Meanwhile, I believe I'll go add a large bottle of Tabasco to the shopping list.