Of Angle Grinders and Buttermilk

By Bill Butler

That Ugly Ugly Tree

In the late Nineties, I won a Ficus Salicifolia at the Azalea City Bonsai Society's (Mobile, Alabama) annual auction.  It had a 7-8 inch base.  Just a few years later a greenhouse heating failure killed it down to a stump.  I emptied the growing pan and tossed the stump into the corner of my greenhouse.  It sat there, ignored, amid empty nursery pots and dead branches, and I quickly forgot it.

By the end of the following summer, the stump had begun to grow a few green sprouts.  Still ignoring it, the bare stump languished in the corner on the bare cement floor of the greenhouse.  After a couple of years, I tossed the stump into a pot, but didn't bother to cover the roots.  Somehow this thing has survived my disappointment and neglect.  This year, it became time to reward its tenacity.

I thought this tree would become a source of cuttings.  After all, Ficus Salicifolia is a vigorous species and despite its susceptibility to frost damage, it is truly hard to kill.  Cuttings are easy to root.  Trees can be cut back hard.  Roots can be cut back hard.  I've been told I can even plant this tree upside down and its roots will sprout leaves and the branches will become roots (an interesting future project).  A recent string of clues came together to change my mind, and my heart regarding this tree.

Exactly what it looked like when I pulled it out of the nursery container. It had sat atop soil, not in it, for several years.

Seen together, the clues are hard to miss:  A friend of mine near Alexandria called me earlier this year to discuss muck; An upcoming GNOBS meeting program will discuss moss; I've been trying to find a use for several slabs I own; A discussion on the GNOBS forums brought up the Salicifolia species. Then, just last week, my welding leathers fell off a shelf when I was looking through my tools.  "Yeah," I thought, "Let's put the little monster on a slab."

Slabs are just made for forest plantings.  The numerous trunks and the rugged slab lead the viewer to think of a natural setting.  The bonsai forest can be seen as being at the edge of a stream bed or jutting out to a cliff edge.  The only slab planting I’d ever owned was killed off by Katrina.  It’s time to again put slab plantings on my benches.

The sprouted stump of the ficus has more than 40 trunks in several clumps.  As seen in the photo, the sprouts came up around the perimeter of the original trunk.  The more I looked at this arrangement, the more I knew this would make a fascinating arrangement.  But before I could mount this on a slab, I needed a finished slab.

Close-up of the numerous trunks.

Let's Carve A Stone!

Joe Day, of Alabama, is the premiere sculptor of bonsai slabs in the Southeastern United States (certainly farther than that).  He has a good eye and a practiced hand.  When he came to New Orleans in 2004 to do a demo/workshop for GNOBS, I asked several questions regarding stone sculpting.  I'm glad that I did.  It's much more involved than simply taking chisel to stone.

Faceplate, Ear Protection, Respirator (NOT Dust Mask!), Face Shield, Welding Shirt, Welding Bib, Welding Gloves

Personal safety is a critical issue when making stone slabs.  Eye protection is the easy guess on equipment needs.  This works rather well for nearly all of the chisel work.  However, to get a good finish on the stone, I'll need an angle grinder with a steel brush wheel.  The grinder kicks out a great deal of dust.  For safety, I use a respirator (NOT a dust mask) or I'll run the risk of developing silicosis of the lungs.  Because I'm using a machine on stone, I also want good ear protection.  Finally, I use a face shield and a vest of welding leathers.  The steel wheel bristles wear away as I grind on the stone.  The wires WILL break off at a high rate of speed.  The face shield and leathers should protect me from serious harm.

I mention all this because for the same reason Joe Day told me this.  Someone reading this is going to attempt to carve a stone slab of their own.  If someone does not take the precautions I've indicated, they run the risk of serious injury, lung damage, vision loss, hearing damage, little bits of steel embedded deep into their flesh, loss of fingers, and more.  Actually the same risk exists even if my recommendations ARE followed.

DO NOT ATTEMPT to do this type of work if you’re not familiar with an angle grinder.  DO NOT ATTEMPT to do this type of work if you’ve never thought of carving slabs like this.  DO NOT ATTEMPT to do this type of work if I’m your only source of information on the subject; you’re going to hurt yourself something awful.  I’m just documenting what I do, but not everything I know, so don’t use this article as your instruction manual.  Find a licensed professional to teach you how to do this before you begin.

How I Carve

Carving a slab begins with selecting the right material.  Prior to Katrina, we had a local company which supplied the area with beautiful flagstones.  I managed to collect several sizes and colors.  I matched the ficus stump/clump with a piece of Pennsylvania Blue Stone.  The other color stone is a Lilac Flagstone.
The blue stone is about 3/4" thick.  The edges are boring and do not taper off.  To create an attractive slab, the edges need to be thinned.  A hammer and chisel make quick work of thinning the edge.  The stone's cleavage is parallel to the broad face of the stone.  This allows for the removal of stone material in small plates.
I carve using a brass hammer and a steel chisel.  Brass is a soft metal and reduces the risk of causing the chisel to chip during carving.  Not the sort of thing I want in my eyes.

Which to pick? The darker stone to the front and right, with the rust stains, is my only Joe Day slab which I got in 2004.

Before I began carving the stone for this particular tree, I had to determine the fronts of both the stone and the tree.  Both decisions were easy.  For this tree, there was a small opening between the clumps of sprouts which lead into the open space within.  For this stone, I liked the way that the curve of the stone draws me in from both sides.  I’d like to say I saw the open-arms look in both stone and tree ahead of this point, but it’s pure happenstance.

The stone I chose after washing it off with water.

Now that I knew the orientation of the stone, I could make decisions on how to carve.  This particular slab is not very thick and has a consistent thickness throughout.  I decided to make all the edges thin out in the same way.  This is only one approach, however.

Depending on what I want, I would use different techniques to carve the stone.  If the stone were twice as thick on one end than the other (or even greater), I could leave one end thick while tapering out thinly to the opposite end.  What I don’t want is the original edge of the stone as it comes from the quarry.  As in bonsai, the features of the stone should be in scale with the tree.  I vary the application of chisel and hammer heads to reshape the edge faces of the slab.

As I thin the edges of the stone, I try to remove the right amount of material from both the top and bottom of the slab.  The edge of the slab should not rest flush on the bench for several reasons: The appearance is better; The slab is easier to lift and move; The edges will better resist chipping over the life of the slab.

Unless I want several smaller slabs from one big one, I never chisel down into the face of the slab.  As I mentioned before, the cleavage of the stone is parallel to its face.  If I chisel into the stone’s face, I have no way of knowing which way the stone will break.

Tool marks are clearly visible after carving. The angle grinder with a steel wheel attachment buffs these out nicely as seen on the right.

After carving, the stone is covered in tool marks.  This is where the angle grinder comes in. Its now time to suit up in my welding leathers and don all remaining safety gear.  The stone needs to be placed on a sturdy level surface, preferably wood.   Clamps or weights are used to hold the stone in place during grinding.

The angle grinder is shown with a steel wire wheel attached.  At full speed, this will buff the smaller flakes of stone at all edges.  The wheel can be used parallel to the stone or perpendicular to the edge depending on my intent. The wheel is positioned so that the stroke of the wheel is pushing material AWAY.  The hammer and chisel have not only removed material from the stone, but they have loosened material as well.  This will come flying off the stone at a high rate of speed.  The entire surface of the stone is buffed with the wheel to give it an even finish and to remove all tool marks.

Carved and buffed. The tool marks have been removed. The stone is nearly ready for its tree.


"Anything worth doing is worth overdoing."

Joe Day signs all of his slabs.  Its a nice touch I want to duplicate.  Joe signs his stones freehand.  I wanted to sign mine neatly with a logo.  I printed the graphics off the computer and taped the printout to the stone.  I used my Dremel Engraver to trace the design through the paper.  I think it came out very nice.

It's not ready until it's signed.


Potting The Tree

The BCI 2009 convention was held in New Orleans.  Among other things, I was in charge of the muck.  This mixture is about 60% Louisiana blue clay and 30% milled peat moss and 10% whole sphagnum moss.  Joe Day recommends adding cow manure.  I would too, if I had any.

I got the clay at a construction site.  Joe Day recommends running the clay through a blender.  My wife does not.  When I got the clay, it had been well dried in the sun and crumbled to very small piece.  I had to grind it out to a cornmeal consistency by hand.  Using a blender would get the consistency down to dusty flour.  I mixed the dry clay with the dried mosses and applied water to the mix. The smaller the clay particles, the more even the consistency of the muck, and the quicker the clay/peat mixture goes from hard granular clay to muck.

After the BCI convention, I stored the excess clay in two 5 gallon buckets with tight lids.  When I opened the buckets a year later, I found the muck to still be pretty moist and useful.  I added a bit more sphagnum moss for preference, and made my muck wall. The wall is there to act as the missing sides of the bonsai pot.  The muck should be made into walls about 1-1/2 inch to 2 inches thick, and at least as high.  This is varied according to need.


Anchoring the tree to the slab can be done in several ways.  Holes can be drilled through the slab like a bonsai pot, however anchor wires running beneath the slab will require channels to keep the slab resting flat on your bench.  Or eye hooks can be drilled into the slab. In either case, drilling through the slab makes me uneasy in that the slab may fracture during the drilling process.  To mount the anchor wires to the slab, I use Quikrete Hydraulic Water-Stop cement.  The ball of wet compound was just over a tablespoon in volume.  The cement dries quickly, so I will not have to wait long until it is dry enough to mount the tree to the slab. To help the cement adhere to the slab, I carve a small 'X' into the slab with my engraving tool. 

Muck wall and anchor wire held in place with hydraulic cement.

Potting the tree on the slab is much like putting it into a bonsai pot.  Add some soil; remove excess roots; put in the tree; wrap the wires around the roots; fill with soil; remove air pockets with a chopstick.  The difference with this particular tree is its massive root/stump thing and it's lack of a mass of thin roots.  Because the root ball was one thick ovoid, I cut 2 inches from the base of the ball using a hand saw.  The massive oval cut measured roughly 10-inches across.  With any other tree of any other species, this would have killed the tree.  However, being a Salicifolia of such a strange pedigree, it will survive just fine.

The tree is "potted".


The League of Moss Collectors

Live moss is used to keep maintain the integrity of the muck wall.  Routine watering will keep the moss alive, but will not wash away the muck.  The trick is finding enough moss to cover the entire wall.

The muck wall will wash away over time. Moss is needed!

I described my project to a fellow bonsai enthusiast.  He tuned me in to a location of moss growing in an out-of-the-way spot.  I have been sworn to secrecy not to reveal its location.  So I'll just post a photo of the moss itself.

The secret stash of moss. I collected about one-fifth of all of the moss in this area.

I give this location high marks for quantity of moss.  It's Mississippi River Sand on top of concrete.  Its ideal for growing moss but little else.  Further, the location is in full sun and thus the moss is durable.  Moss collected in the shade is often quickly burned by full sun plantings.  As this is a tropical planting, full sun is called for.  On the down side, the location has a  slightly treacherous terrain and no nearby parking.  This moss is great moss and worth the walk and terrain.

The moss is too dry and clumpy for immediate use. It will need to be cultivated before I can place it on my muck wall.

Before I could place the moss on the slab, I wanted to cultivate it a bit.  For that, I use a solution of 50/50 buttermilk and water. The water helps the spray bottle work.  I removed the dried sand from the back of the moss and placed it out onto wood and cinderblock bricks.  A sheet of cheesecloth helps to keep the moss moist.  The cheesecloth should be lifted off the moss at least every other day to keep the moss from growing up through the weave.  The buttermilk solution is sprayed on the moss every second or third day.  I figured as long as I had the solution ready, I may as well spray it on every bit of moss in the vicinity.

Cheesecloth is used to keep the moss moist. Buttermilk can be sprayed through the cloth every second or third day. Be sure to lift the cloth every other day to keep the moss from anchoring to it.

This plan worked up until I got sick.  While running a fever will not keep me from watering my trees, it did keep me from tending the moss.  I was unable to periodically lift the cheesecloth.  Thus moss anchored itself to the cloth as it grew.  Removing it caused me to break the nicely growing sheets I needed for the muck wall of the slab.  Luckily, moss on the sides of my terracotta pots and bench supports were benefitting from my buttermilk routine.  I had enough to complete the slab.

I was hoping for thick sheets of moss from my cultivation attempt.  This would have resulted in nice thick mats of moss.  To apply these to the muck wall, make small U-shaped staples out of floral wire to pin the muck in place.  That works for thick mats of moss. However, what I had available was paper thin sheets of moss scraped off of pots and bricks.  The staples don’t work to hold this in place.  To apply thin moss, I simply moisten the muck and push the moss onto its surface.

The finished tree with moss applied.

Future Development

I’ve got more than 40 “trunks” growing on this one slab.  Ficus Salicifolia is a vigorous species.  Given what I’ve done to it, I may have some trunks die back.  Three weeks after potting, however, everything seems to be going just fine. 
My initial design of several clumps in a “fairy circle” is going to evolve over time.  The first task is just to maintain an untangled mess of trunks.  Once I’m certain that the trunks are healthy, I’ll thin out any obvious problems, then I’ll watch for taper issues with the trunks.  Next Spring I’ll defoliate the entire arrangement and cut the ends to encourage branch development.
Eventually the trunks, and perhaps the limbs, will begin to fuse together.  This species is too vigorous in this climate (New Orleans, USDA Zone 9b) not to expect that.  At that point, I’ll rethink the style and perhaps the stone.  I’ve located a new supplier of stones in a variety of colors.  I’ll be ready.


Bonus Photos In 3D

I've created two photographs using a dual-lens 3D rig. I've got two versions of each photo. One, the familiar Red/Blue anaglyph where you need special glasses to view the imge. Second, the images are in "Cross-Eyed" 3D where you do not need to use special glasses, but you do need to cross your eyes until the images overlap.

LINK HERE to see the photos.

I included the photos to allow you to see the depth of the circle of clumps. If this proves useful, drop me a line and let me know. I think bonsai could benefit from the use of 3D documentation.

Copyright © 2010 by the author and the Greater New Orleans Bonsai Society. All rights reserved.

No part of this publication may be reprinted, copied or otherwise reproduced without written permission from the editor.

Updated September 17, 2010