Faux Bois Step by Step (with pictures!)

A "lost art" is only lost for people who don't seek to learn it.

Inside the ninety year old faux bois concrete, the steel has slowly decayed where, as the concrete absorbs moisture, water has been trapped in the air pockets that were left in the original construction. In addition, as this moisture has drained and seeped out for ninety years, it carries with it a kind of "flowstone"... a Calcium "stalagmite-like" material that has "self- sealed" much of the original steel rebar and mesh, leaving most of it "sound material".
The structure is not at risk. I find the failed material (usually only the outer sculpted "skin") by listening for a hollow sound, tapping with a metal tool. When it sounds right, the tool "rings" indicating sound material. This original material will go forward in time without my help. The hollow sounding material is removed and replaced with the same techniques and the hindsight of what made it fail. Using better practices for the replacement, I work to avoid leaving any air pockets or voids with modern concrete (mortar or grout) and acrylic fortifiers and current best practices.

1. Determine sound/unsound material and remove decay

One of the 100 faux bois trees with its existing decay. Expanded metal mesh was patented in England by John French Golding in 1884.

Photo document existing condition
Tapping with a metal tool, listen for hollow sounding decayed material - the "sound" material "rings" and will remain
Remove all the material not well adhered
Wash dirt and fine lose material from exposed inner surface

Close-up of old faux bois concrete showing a failed character "knot" and bark effect. The backside of these pieces have the original rusting steel mesh that caused the delamination.

The original rebar armature was a single twisted square steel bar. Twisted to provide better interlocking strength with the concrete. Rebar today is manufactured with deformations (barbs) for the same reason. Next, a mesh "cage" was wired in place and stuffed with a somewhat dry/stiff concrete mix. (This technique created voids for water to be trapped as it absorbs moisture.) Finally, after this was hard, the outer layer of fine mortar/grout was applied and sculpted while in a wet state.

2. Treat the Rusting Metal

Treating the rusting steel with Phosphoric Acid also cleans and etches the faux bois concrete without damaging it where the new work will be applied.

Chemically treat the exposed metal with phosphoric acid to arrest and convert the rust

Apply self-etching metal primer (aerosol spray)

3. Fasten Support Mesh

Copy shape of void by making a kitchen foil pattern
transfer pattern to new galvanized expanded metal mesh ...."Diamond Lath"
Cut mesh to shape and fasten with building adhesive to keep it in place

I am using aluminum kitchen foil to make an accurate pattern to transfer the shape to new galvanized metal mesh applied in the photo on the right.

Center handrail faux bois tree with metal treatment: Phosphoric acid followed by an aerosol self-etching zinc primer.

The same faux bois tree with new galvanized mesh applied. The dots of building adhesive hold it in place for the next step, filling with mortar.

The galvanized steel mesh has been filled in and new bark texture has begun. The rough "stucco-like" surface is produced with a heavy scrub brush tapping the surface. This pushes it through the mesh and into all the nooks and crannies eliminating air pockets that can lead to future decay. My task is to correct the flaws from the original techniques and reverse the decay, leaving it to continue self correcting the sound material. As the finest minerals move with the moisture, it "coats" the old steel that has not failed.

4. Apply Mortar

Fill the mesh with acrylic fortified mortar being careful to avoid leaving air pockets.
This is accomplished by tapping with a heavy scrub brush which leaves the surface rough to help the next step.

The faux bois concrete handrail before restoration shows its twisted square steel reinforcing exposed. This type of rebar was patented in in the United States by Earnest L. Ransome of San Francisco in 1884. It is described as the first "true" rebar because it creates a "lock" with the material surrounding it and adding to the overall strength, thereby, "reinforced" concrete.

The faux bois concrete handrail has new galvanized metal mesh applied where the original "skin" had failed and the rebar was exposed. This was prepared with the metal treatment steps. It will be filled with wet mortar in the next step.

5. Sculpt Surface

Mix acrylic fortified grout (finer sand than mortar)
Apply and Sculpt in wet state.

Faux bois concrete bark details being added.

Matching Original Style

Close up of sculpting wet "bark" with roofing nail tool....

Common tools used to achieve matching texture are: cake decorator bags, stiff brushes, table fork, small trowels & knives, and my favorite discovery: A ROOFING NAIL !
The nail was a very substantial discovery I made in the early weeks of the project as I puzzled over how the original artist created the distinctive bark texture that is so "consistently inconsistent" and so much a part of the "personality" of the best original work. While observing some of the removed pieces, the side view or cross-section revealed a "T"shape in the "valley" or grooves that nothing but a nail could have made. I was very excited the next day with my new "tool".....I had unlocked a ninety year old secret!

It is a very interesting task to both try to embody the previous work done, while also having an individual style. Unlike most restoration projects, Terry does not have to go to great lengths to protect the exact original style of the craftsmen who have worked on these trees before him because their names were never recorded. Often in conservation and restoration there is a tendency to try to protect the original work, rather than re-do it or change it. By finding interesting tools to best embody the original techniques, Terry balances the look of his new sculpting with the old.

Notice the newly sculpted work on the upper part of this tree without the color "staining". The horizontal branch has just been color "washed" and will get "dry-brushed" highlights with an un-sanded grout that matches the lightest tones of the old original work.

6. Color

Mix an acrylic sealer with tints to make darker “aged” colors (a water consistency to soak in), apply with spray bottles
Lighten the darkened area with un-sanded grout that color matches old work with "dry brush" technique highlighting the raised textures

The South faux bois concrete handrail is fully restored!