Design of Sekimori Ishi for Pedvale

This is a design for Sekimori Ishi, to allow construction on-site at Pedvale. The sculpture consists of an unmodified granite boulder, about 4 feet tall, (1.2 meters) and 5 cast iron pieces which are bolted together. This will be permanently sited outdoors at Pedvale Open Air Museum. The proposed sculpture is an iron and granite representation of a sekimori-ishi, which is a feature of many Japanese gardens.. This sculpture was inspired by Nabuo Sekine and the Mono Ha movement. Mono Ha is a Japanese art movement related to Land Art, which encouraged the production of objects, usually of natural materials. If you grow up in Pittsburgh, cast iron is a natural material.


The sculpture is based on the traditional sekimori ishi, as used in Japanese gardens. The term means “boundary guard stone”. As shown below, this is a small boulder, tied with garden twine, which forms a handle. Sometimes, this is a metaphorical warning to “stay on the right path”. At other times, it refers to a danger or unpleasantness along that branch of the path. It can also be a request for privacy. This is a polite request, that can be easily ignored by stepping over the stone or moving it.

Sekimori ishi at Chicago Botanic Gardens

Sekimori ishi at the Chicago Botanic Gardens

This is the original maquette, solid aluminum cast in one piece around a granite stone. The full size sculpture will mimic this visually, but the “arms” will be hollow, and will not join at the bottom of the stone. The “ring” has been slightly modified, and rotated 45 degrees. It should appear possible to pick up the sculpture with the lifting ring on the top, but it will actually be lifted with a sling, and the iron pieces are not actually used for lifting. The idea is to give the Japanese symbol the style of 19th century industrial iron. This could be interpreted as a post-industrial comment on the abuses of 19th century industrialization.
granite and aluminum

The arms will be made at Pedvale from gray cast iron. They will have an open rectangular cross section, with the open end facing the boulder, which is approximately 4 foot tall. (1.2 meters).
Dimensions of the arms are D=6 inches (15 cm), B= 3 inches (7.5 cm) t=1/2 to 5/8 inches (1 to 2 cm), depending on material available to make the casting patterns.

cross section of arms

cross section of arms

There are 4 arms, at right angles to each other. For identification, label them north, east, south, and west, like a compass. They do not need to be oriented to the compass direction when the sculpture is sited.

The arms will be curved to fit the boulder, and have squared-off ends. They will be bolted to the boulder through a hole in each end. The bolts, made of threaded steel rod, will be anchored in the boulder using a commercial, long set up time epoxy.



The lifting ring has been re-designed to have a round, 12 inch diameter circular hole. (20 cm in diameter). This should be large enough, so that viewers can not get their heads stuck in the sculpture.

Top Ring

top ring

The ring will be cast in one piece with a cross shaped plate at right angles to the ring, with a square piece between them.


bottom of lifting ring piece.

6 inch (15cm) square middle layer

square middle layer of lifting ring

The plate will be bolted to the 4 arms with 1/2 inch diameter threaded rod,or a metric equivalent. This will pass through the upper end of the arm, then the cross shaped part of the lifting ring, them into an epoxy-filled hole in the boulder. Loc-tite or something similar will be used to prevent the nuts from being removed.

assembly of arm and lifting piece.

assembly of arm to lifting ring piece

The arms will slide over the protruding ends of the cross shaped lower piece of the ring assembly, in a mortise and tennon joint. There are two threaded rods holding each arm, one at each end. The rods are placed and set in epoxy after the lifting ring and the arms are placed and fitted to the boulder.



As the arms do not actually cross at the bottom, the first few inches of the sculpture will be buried in gravel, to hide the lower end. This should make it appear that the arms cross under the boulder. If possible, I would like to use very small crushed limestone, and ram it into place. This may be mixed with local clay, if it is available. I have see lime-clay-flint foundations over 1000 years old in Winchester, England.


As a final addition, I would like to bolt a large piece of cast aluminum to at least one of the lower arm ends to act as a sacrificial anode. This can be any locally acquired scrap aluminum. Since aluminum is more reactive than iron, this will corrode in preference to the iron. This technique has been used to protect street railway rails, plumbing, and marine vessel hardware. I might cast these pieces at home, before the conference.


One thought on “Design of Sekimori Ishi for Pedvale

  1. Why not incorporate the spacer into the bottom of the lifting ring, so the ring slides into the space between the arms and is held in place by the two bolts between North and South arms? Also, I’d fasten the bottom of the arms down somehow; I’m afraid the freeze-thaw cycle will slowly push the bottoms out like a big lever. Maybe just driving a tap-con through the bottom of each arm into the boulder will alleviate this problem.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s