Saturday, August 19, 2017

Restoration, Renovation, Rehabilitation, Conservation: What Does it All Mean?

When talking about historic architecture we often use terms such as restoration, renovation, conservation or rehabilitation.  However, these terms have very specific meanings when used in particular contexts which can be quite different from how they are commonly understood.  It can be especially confusing when speaking to preservation professionals who use these terms following established definitions.  For instance, we frequently hear people describe "restoring" their 1890s home by remodeling or updating the kitchen and plumbing or installing French doors.  Is this truly a restoration?  Keep reading to find out how a preservation professional uses these terms so we can all be on the same page and avoid confusion.

Restoration: A true restoration is the process of returning a building to its appearance and condition at a specific period in time. This means making a house look exactly like it did at a certain date, including recreating the wallpaper, matching historic paint colors and matching or reproducing fixtures and hardware. True restorations are quite rare and largely limited to house museums like Mt. Vernon or Monticello. Many of the things called restorations really aren't.  The example I gave above of remodeling and updating a kitchen and plumbing is not, in fact, a restoration.

Renovation: If remodeling and updating a kitchen and plumbing is not a restoration, what is it? It is a renovation. Renovation is the process of making something look and function like new.  Replacing period HVAC, plumbing and wiring or adding French doors is a renovation since you are making an historic building work and function like a new building according to today's standards.  Although a renovation can be quite sensitive to the historic nature of a building and preserve as much as possible, it is a different act.  Although there can be some overlap between restoration and renovation, it is good to appreciate the differences.

Rehabilitation:  Rehabilitation means something very similar to renovation, but it is often used in a slightly different context.  Rehabilitation is the process which seeks to preserve the historical portions or features of a building while making the building compatible with a new use.  A good example is rehabilitating a brick, 1870s horseshoe factory to be used as lofts or commercial space.  This term is often used in conjunction with tax credits which encourage the preservation of historic building for income-producing businesses.

Conservation: Conservation is also fairly rare and normally done in house museums.  Conservation is the preservation of particular building features for the future.  In other words, it is the process of arresting decay or decline so that the original workmanship and materials survive as they are now found.  This might mean cleaning and protecting a fresco in a church so that it doesn't continue to be degraded by leaking water or soot.  It is different from restoration because restoration would mean returning the fresco to its appearance when the church was built. However, restoration can be a destructive process because, in order to make the fresco appear new, you would have to alter or destroy some of the original workmanship.  Sometimes the materials and workmanship have such historical value that we simply halt their decay and leave things as they are so that we can appreciate them as examples of historic craftsmanship.

Is your woodwork hungry? Should you feed it?

We all know there is plenty of advice on the internet and that some of it is very good and some of it is poor.  One topic that I encounter frequently as a preservation consultant is the care of historic woodwork and furniture and the apparent need to feed, nourish or moisturize wood.  Unfortunately, most of the information circulating on Facebook and the internet about this is quite incorrect.  Although I may be a voice in the wilderness, here is my attempt to set the record straight.

Your woodwork does not get hungry. It does not get thirsty. It does not need to be fed.  You do not need to give it a drink.  Examples, testimonials and recommendations of people doing so are legion but they are misguided.  Moisture in your woodwork or furniture is a function of the ambient humidity in its environment.  Humid air means wood has a higher moisture content and drier air means wood has a lower moisture content.  It is as simple as that.  What is important is to limit the frequency and amplitude of swings in humidity and temperature because this cycle of expansion, contraction and moisture content will cause wood to swell and contract and can degrade historic finishes or cause cracks and checking.  It is important to moderate these swings to the extent you are able by limiting changes in temperature and humidity levels.

“Feeding” your woodwork or furniture with linseed oil, tung oil or orange oil will not replenish moisture.  After all, how can oil replace water?  If you are thirsty do you grab a bottle of Wesson oil out of the pantry and take a drink?  Of course not, and your woodwork is no different.  Oil doesn’t feed wood either, but it can be quite harmful.

There are two types of oil commonly used on woodwork: Drying oils and non-drying oils.
  • Drying oils: These include linseed oil and tung oil. They are called drying oils because the molecules cross link or polymerize when exposed to oxygen.  That is, they harden or form a film.  This is why they are used in varnishes, paints and other finishes.  They are harmful because continued use will saturated the wood and, when they drying oils oxidize over time, they will turn dark or black. This is irreversible.  The real tragedy is that this process can take years or even decades.  People will swear up and down that this is untrue, but this is only because they haven’t been around long enough to witness the entire process.  Ask any furniture conservator what they have seen.  Indeed, many museums have wonderful pieces of furniture that have been ruined because they were repeatedly sopped with linseed oil decades ago and subsequently have turned dark or even black.  The key word to remember here is CONTINUED use.  Although drying oils were used historically to make varnishes, paints or other finishes, it is the continued, repeated and liberal use of drying oils that saturates the wood and can cause damage down the road.
  • Non-drying oils: These include orange oil and lemon oil which are often mixed with beeswax. They are called non-drying oils because they do not cross link like linseed oil and remain liquid or semi-liquid.  Although they aren’t harmful like drying oils can be, they don’t nourish or feed wood.  When used on vanished wood they sit on top of the existing varnish and, over time, will form a gummy film after the volatile elements have evaporated.  The gummy film can be quite thin but still will attract dirt and grime and create a mess that can be especially nasty on molding and in corners.  To combat this people will apply more orange or lemon oil to revive it.  This does restore a shine temporarily, but the process continues.  Non-drying oil should never be used on unfinished wood because the oily gunk will penetrate the wood and cannot be removed.

What are we to do to care for woodwork and furniture?  A paste wax polish on a clean surface.  Woodwork should be clean and dry and covered with a paste wax or beeswax polish (with no orange oil!).  There are plenty of good products on the market that work well. I make my own paste wax using an 1850s recipe that I tint to match the color of the woodwork.  This is one case where what they used years ago continues to work today.  A yearly coat of wax is all that is needed to protect your woodwork or furniture.

One more thing to remember.  Never use anything out of an aerosol can since these sprays contain silicates which can saturate the finish and can't be removed.  Natural wax finishes are the way to go.

I know there are people reading this who will strongly object and assert that I am uninformed and completely incorrect.  They will claim they’ve been using products containing linseed oil to condition their woodwork for years with no ill effects.  Well, I have made my case and you are free to do what you wish.  However, if have any doubts and are curious, feel free to Google the American Institute for Conservation of Historic and Artistic Works and see what they say.  Or, keep saturating your woodwork with linseed oil and hope for the best.

Saturday, March 4, 2017

Pressure Washers and Painting: Should You or Shouldn't You?

There are conflicting messages about using pressure washers when prepping building exteriors for painting. Some insist that pressure washers should never be used while others maintain that they are just fine and use them both for paint removal and cleaning.  Which is accurate?  As with most things, the truth is somewhere in between and depends on circumstance.

First, it is true that pressure washers should never be used to REMOVE paint.  In order to remove paint effectively you need to dial the water pressure up to blast away the old paint layers.  Unfortunately, this also means that the wood siding or stucco can be damaged or eroded.  This is especially true on historic buildings because they typically have areas which are in good and others in poor condition (often on the same piece of siding).  Remember, pressure washers are powerful enough to mar stone such as granite, so even at a relatively low setting a wood substrate can be affected. Some would argue that they can dial the pressure down so that it won't damage the wood.  However, in order to to make a pressure washer effective, the pressure has to be set fairly high.  The photo below shows clapboards where wood fibers have actually been torn away from the surface.  The best and safest way to remove paint from historic exteriors is by scraping and sanding because it allows you to vary pressure according to the condition of the siding.

Another problem with pressure washers is their tendency to drive water into cracks and gaps and saturate the siding itself or the sheathing behind it with water.  When water has been driven behind the siding it can take weeks for it to dry.  As the water evaporates and escapes through the siding as a vapor it can cause paint failure. Even the best primers and paints will not adhere to damp wood or wood releasing water vapor.  The photo below shows siding on the same building that has more eroded wood as well as cracks around nails which would allow easy access to water from a pressure washer.

Does this mean pressure washers should never be used?  No, not really.  They can be fine when used at their lowest pressure setting as a means to CLEAN a wood or stucco surface. Care must be taken to direct the water stream at a correct angle so that water won't be driven underneath clapboards, battens or molding.  However, a garden hose with a brush is just as effective and far less likely to damage the wood siding or drive moisture behind the surface.   As is often the case when working on historic buildings, shortcuts can lead to poor results and there usually is no substitute for a little elbow grease.

Saturday, January 14, 2017

The National Register of Historic Places

Historic Design will donate free architecture research services for a local institution, business or individual in 2017!  Click here to learn more.

We frequently see and hear about historic buildings and other structures being listed on the National Register of Historic Places. However, it isn’t clear to many what the National Register is and what it really does. Does it protect a house from demolition?  Does it prevent owners from building an addition, remodeling the kitchen or adding a bathroom?  If your church is listed on the National Register does it mean you can't display the cross?
A centerpiece of the landmark 1966 National Historic Protection Act, the National Register of Historic Places is an official list of historic buildings, structures and places that are considered worthy of preservation. The National Register is administered by the National Park Service and is part of a larger federal program which coordinates and supports private and public efforts to identify, evaluate and protect our Nation’s historic resources.  The listing is largely symbolic and itself offers no real or statutory or regulatory protection.  In other words, listed buildings can be used, altered or even demolished in any manner, for any reason and at any time by their owners.  Despite what you may hear, the National Register itself absolutely cannot prevent you from remodeling your kitchen, painting the exterior, adding a bathroom or displaying religious symbols.
If the National register only provides recognition of a property’s historical, architectural, or archaeological significance without any regulatory teeth, what is the point of listing a property? First, listing a property is important as it does distinguish it and encourages the community to recognize and appreciate it historical and cultural significance. This is not insignificant as preservation has becomes a larger part of city planning and efforts to rebuild communities. Second, while the National Register itself is symbolic, inclusion on the Register can make the listee eligible for grants for restoration and rehabilitation, state, local and federal tax credits, preservation easements and some building and fire code alternatives.  Although these programs and benefits usually require additional qualifications and regulations, a listing on the National Register is the first step towards eligibility.
Inclusion onto the list is considered according to one or more of four criteria:
  • Criterion A: The property must make a contribution to major patterns in American History.
  • Criterion B: The property is associated with significant people of the American past.
  • Criterion C: The property has distinctive characteristics in its architecture and construction, including having great artistic value or being the work of a master.
  • Criterion D: The property has yielded or may be likely to yield information important to prehistory or history
The application process can be quite involved and complex.  It includes documenting the building or property following established standards, historical research, evaluation of the building or property’s physical state (i.e. does it retain enough of its original, historic fabric), identification of its historical context and its eligibility according to one or more of the criteria.
The National Register application can be completed and submitted by anyone, although many property owners and public institutions rely on preservation professionals for part or all of the application.  Consultants who are familiar with architectural history, regional or local architects and important local and national historical patterns can be particularly helpful.
If you have any questions about your historic house or building and the National Register, feel free to contact Historic Design Consulting.

Sunday, November 13, 2016

Historic Design will donate free architecture research services for a local institution, business or individual in 2017.

People who choose a career in Historic Preservation and Cultural Resources Management do so for a variety of reasons.  One thing that is common to us all is a deep and abiding interest in preserving our built heritage. This certainly is the case for us at Historic Design Consulting.  In an effort to contribute to our community Historic Design Consulting will donate research services for a worthy project in the  Minneapolis/St. Paul metropolitan area in 2017.

We will accept applicants through September of 2017.  This is not a contest and we do not have any formal eligibility requirements.  We will choose a project depending upon our schedule and the scope and type of the research project.  This could be a context study for a National Register nomination, property evaluation or a general research report for a home or business.  We do reserve the right to accept or deny project for any reason.

If you have any interest, please contact Historic Design Consulting and tell us a little about the project.  We'd like to know where the building is, what sort of building (house, business, ???), when it was built, and what you would like to learn about it.

We are looking forward to hearing how we can help our own community preserve its architectural heritage!!!

Sunday, November 6, 2016

Historic Plaster and Somebody's Horse

Plaster has served  as a durable coating for interior walls in both high style and common buildings for centuries. 19th century wall plaster was made from four ingredients: lime, sand aggregate, fiber and water.  The lime was the most important part of the mix as it cured and hardened much like concrete.  Sand was a filler that also added structure.  Water was the catalyst and the fiber held it all together while the plaster mix cured and hardened.   Gypsum replaced lime in the 20th century because it set more rapidly and provided a harder, more durable finish more quickly.  Since gypsum sets in minutes and cures in weeks (lime plaster required months to cure before it could be painted or papered), it made the addition of fiber unnecessary.

The lime was often produced in kilns from local limestone deposits.  The sand aggregate usually came from a nearby river or lake which could also provide fresh water for mixing. What was the source of the fiber?  More often than not, it also came from local source: an unsuspecting cow or horse from the barn out back.

I recently attended a workshop on repairing historic plaster organized by the Preservation Alliance of Minnesota.  Our leader for the day was Anders Christensen of TigerOx, a Twin Cities painting and plastering company that frequently works on historic buildings. Rather than spending the day in a classroom we had the privilege of  working on an actual historic site, the 1867 Andrew Peterson farmhouse in Waconia, MN.

In high style houses the plaster was applied in three coats over split or sawn lathe. The first two coats, called the scratch and brown coats, were thick, coarse and contained the animal fiber with lots of aggregate. This constituted the bulk of the wall plaster.  These two coats were finished with a thin layer of finish plaster. The finish coat had little aggregate and was troweled to a smooth finish.

However, when we looked at the walls in the Peterson house, we found something quite different. The Peterson house was built by Andrew himself, who was a farmer and not a professional carpenter or plasterer.  Rather than three coats, we found one, rather coarse coat of plaster.  This is not uncommon at all in vernacular buildings such as farmhouses or city buildings which weren't built by professional tradesmen.        

This is one of the holes we repaired in the Andrew Peterson farmhouse.  Notice
the single layer of plaster with a sand aggregate. 

What was also interesting was what you could see in a few chunks of loose plaster. The animal hair used to bind the plaster was quite obvious.  I'm not sure what sort of critter donated its hair in 1867, but it was chestnut brown and rather soft. A horse, perhaps? Whatever it was, it is long gone. That is, with the exception of its hair, which survives 150 years later in the walls of the Peterson farm house.

A piece of plaster with the animal hair fiber.

Something else that interested me were traces of paint on another piece of plaster.  I noticed a few remnants of a light, purplish-blue paint.  The color is a light pastel which was common in house interiors into the 20th century.  I suspect it is a calcimine or distemper paint. Calcimine paints were water based and fairly durable because the pigments were bound to the wall with size, or diluted animal glue.

Another piece of plaster with a few remnants of what appears to
 be a light, purplish- blue paint

The next time you find yourself in a 19th century home, take a look at the plaster walls.  Is it coarse with lots of sand or is it troweled smooth and flat?  If it is smooth, it probably was applied by a skilled tradesman.  If not, it might have been plastered by the homeowner himself.  In either case, it is likely some sort of quadruped also made its own, valuable contribution.  

Wednesday, September 7, 2016

An Interesting Artifact for the Fan of Historic Homes

An important ritual for many American men during the 19th century was a weekly trip to the barber shop for a shave. The barbershop was a social hub in large cities and small towns alike as men congregated to gossip, do business, read the paper and get a professional shave. The shave was a multi-step process where barbers softened the beard with hot, moist towels and conditioned the skin with scented oils. They then used a porcelain shaving mug, badger hair brush and scented soap to create the lubricating lather needed for a close shave with a straight razor.  

Plain porcelain shaving mugs are quite common today (after all, every man had one) and aren't particularly interesting. However, there is one, less common type of shaving mug that is quite interesting and offers a glimpse into the life of a tradesman in the 19th century. 

The discovery of Germ Theory by Louis Pasteur in the 1860s led to the creation of sanitation laws that required a barber's clients to have their own shaving mugs which could not be shared with other patrons.  Blank shaving mugs were imported from France and Germany and personalized by painting the man's name in elegant, fraktur calligraphy.  Sometimes a scene was also painted on the mug which depicted the man's profession or trade.  These occupational shaving mugs were displayed in the barber shop and served as a type of advertising.  When someone went looking for a painter, carpenter or lawyer, they could stop by the barbershop and check out the shaving mugs to find the professional they needed. 

Pictured is a example of an occupational shaving mug for house painter.  Although detail is lacking, we can see wooden barrels which would contain linseed oil and white lead.  The painter is standing on a scaffold which appears to be supported by ropes and pulleys.   At his feet is a pail of paint. The other object is likely another pail which might hold his brushes or other things such as rags or a pumice stone for smoothing rough wood.  Interesting for the historian and colorist is the entrance door.  We can see that the door's rails and stiles are painted a lighter brown and the panels another, darker brown.