Visitors often ask what my favorite thing about the Former Governors’ Mansion State Historic Site is, and my answer usually draws a look of confusion from them. They’re expecting me to say something grand, like the staircase or the massive pocket doors. My answer is something small, but not insignificant--nails.

I love nails! Nails can tell you so much about when something was built. When I see a square cut iron nail sticking out of a piece of trim, I don’t say, “I need to pound that back in.” I get excited because that nail just verified that the trim was installed before 1895.

Square cut nail in an exterior door frame that has pushed out over time from seasonal contraction and expansion. Many layers of paint can be identified, with just a hint of the original 1884 brick red color showing. This nail was pounded in more than 130 years ago.

When the mansion was built in 1884, the steel wire nail we know so well today was in its technological infancy, with only about 10% of all nails produced being small steel wire nails. By the early 1890s the steel wire nail had begun to replace the square cut iron nail. By 1895 mass produced stocks of cut nails had been depleted, making it rare to find buildings constructed with them.

Steel wire nail protruding from an early, but not original trim piece in the parlor of the mansion. The manufacturing tool marks on this nail indicate that it could have been pounded in any time after World War II.

Knowing this little piece of history, I can look at a nail sticking out of a board--be it interior trim, framing wood or siding on the mansion-- and roughly determine when it was installed. Combine that with the type of finishes, thickness of the wood and written/oral histories, and we can nail down approximate dates on mansion remodels.

A great example is the mansion attic playroom’s built-in toy boxes. Oral history suggests that Governor Langer had the attic finished into a playroom in the 1930s for his children. Examination of the toy boxes shows they were built with steel wire nails, and the wood was modern dimension lumber, which became the standard around 1900. These two clues seem to corroborate the 1930s construction date for the toy boxes. But while examining the toy boxes to find out what kind of nails were used, a third clue was found; the signature of Governor White’s young son Edwin.

Edwin White’s childhood signature.

Governor White was in office from 1901 to 1905, which was a perfect time frame for the use of steel wire nails and modern dimension lumber to be combined in the construction of the toy boxes. Good bet that the toy boxes were built during Governor White’s occupancy of the mansion rather than Governor Langer’s!

Next time you are walking through a historic building, trying to puzzle out when something was remodeled, go find some nails. For something so simple, they can tell you a lot.

Susan is an architectural historian who loves old houses, barns and schools. She reviews projects that might impact cultural resources and researches earthen construction.

Welcome to A&HP’s initial processing lab, sieve sorter in foreground. For more information please see blog.statemuseum.nd.gov/blog/easy-question

Archaeologists and architectural historians use initial processing labs or wet labs, containing sieves, to discover tiny bits of evidence that measure big changes in technology. We included one of these rooms in the recent expansion at the Heritage Center. It is used to sort and process artifacts in the Archaeology and Historic Preservation Division (A&HP). The sieve stack (also known as a size-grader) and sorting trays help scientists sort soil, artifacts, and organic material. Researchers are usually searching for objects or fragments of objects that someone made or modified at some time in the past.

In northern plains archaeology, detailed procedures set out in 1989 by Dr. Stanley Ahler outline how to quickly make sense out of hundreds of bags of cultural material by sorting and weighing according to size grades. Viewed as an especially useful way to analyze lithic debitage (the flakes of stone that are removed from a cobble or preform when someone makes a stone tool), archaeologists statistically analyze hundreds or thousands of flakes that have been sorted by size. By doing so, researchers can gain new insights into methods of stone tool production over thousands of years.

Clean ordinary sand under magnification.

Architectural historians and masons also use such labs, equipped with sieves, microscopes, and Munsell color charts. They need the same tools to determine the best match for repairs or repointing between stones and bricks. These researchers try to match the mortar being used for restoration to the historic mortar. To match the sand in a mortar sample taken from an old brick or stone wall, you must first remove the binding element by digesting it in acid. If the original masons used a lime-based mortar, the lime will bubble away, leaving clean and rather attractive sands behind, as seen under the microscope. If the original mortar used a Portland cement, the acid digestion process will probably leave some hard chunks of cement with the sand.

Although Portland cements were known earlier, this technological change from lime mortars to Portland cement became widespread in the 1930s. Use of Portland cement was a fundamental change in building technology. Much of the art and science of lime-based mortars was nearly lost when mixes became far more standardized using Portland. Careful analysis of historic lime-based mortars and maintaining libraries of those recipes allows for nearly exact replicas in mortar when applied next to historic mortar.

Here both new bricks and new mortar needed to match the originals on the left and right of the photo. The architectural historians decided to match both as they were originally made rather than try to match the currently worn brick through artificial antiquing. The mortar will weather out in a rainy season to wash away the fines and leave the sand more exposed. Photos by S. Quinnell

So the same laboratory equipment is used in different applications to discover more about our pasts. In northern plains archaeology the wet lab allows analysis of many minute pieces from our ancient past, from Paleoindian big game hunters through the days of military forts. Similarly, mortar analysis performed with this same equipment can be used to understand changes in building mortar technologies from the earliest stone and brick buildings to the structures of the recent past.