Cob Bench on the corner of

4ht Street and F Street in Arcata, CA.

This was a class project of Patrick McAuley, but couldn’t have been done or started with out the great amount of help of Lonny Grafman and Kirsten Thompson and everyone else who was involved. Thank you to all.

These are the people that let us build the cob bench in their garden.

These are the materials. You can see piles of river rock, sand, and soil with high clay content. They are covered by tarps to keep them dry.

Here we see a wall of urbanite, which is reclaimed sidewalk from HSU. Also a ditch has been dug and filled with river rock. This is the foundation.

This is the first layer of the foundation. It is a puzzle of urbanite with river rock filling in the cracks. There were two layers.

Cob is being fixed by foot power. You want to first mix the sand and clay and water. Once that is mixed, you can add some straw and mix that in.

The consistency of cob should be such that when you pull up on one side of the tarp the cob rolls and peals off.

Then you want to make the cob into melon sized balls.

We moved the cob balls from the cob work area to the cob bench construction area by passing the balls hand-to-hand in a bucket line.

Here is Kirsten telling everyone how to apply cob. You basically want to slam the ball into the rock so that it will stick. You don’t want to slap the cob because it will bring different ingredients to the surface.

Adding cob to the foundation.

We see the first layer of cob is already done. This will be the bottom of the seat, where your bum goes. Now the foundation for the back is being set.

Don’t forget to try out the seat, it will be very difficult to change later.

Adding more cob.

These are some of the hard working students in the Engr 305 Lab of Fall 2003 that helped construct this cob bench on the corner of 4^th street and F street in Arcata, CA.

These are some of the others.

As layers keep added on you wan to be sticking holes everywhere, this will allow the cob to dry faster. Also you want to take your stick and drive it through the wet top layer and through the lower layer. This will grab a piece of straw and pull part of it into the other layer. After the cob dries, the straw will act as rebar.

This is where the class finished. This is a lot to complete in a few hours. It just shows you that if you want to do something big, it will save you a very large amount of time to through a cob party.

In the weeks that followed the work crew got significantly smaller.

Before adding a new layer of cob on top of a semi dry layer of cob you want to wet down the area. This will help all the cob parts to become one and the structure will be more

stable.

This is the cob bench done, but with out a finish. Here it is rough, straw sticking out, and wouldn’t last too long in Arcata rain.

This is the start of the plaster phase. The cob plaster we decided to use was 3 parts clay, 2 parts grated manure, and 1 part sand. Here is Kirsten grading manure with a little friend. Manure can be replaced with shredded straw that can done using a weed whacker and a bucket.

Cob is fun for all ages, babies included, and don’t forget to involve your pets.

Plaster batches are a lot smaller then cob so we mixed it in a wheel barrel.

This is a close up of the raw cob with a little peek of the plaster finish.

Just like in between cob layers, when you add plaster to a dry cob area you want to wet down the area. The different part about the plaster adding is after the area is wet you then want to apply a smear of slip.

This is slip. Slip is supersaturated clay. Just put the highest content of clay you can get and put it in a bucket, add enough water to cover the clay after mixing a few times. Then let it soak over night, mix again and soak again. It should be really slippery.

You want to add the plaster in the up direction. When it is on there then you take a trowel, a flat piece of wood or metal with a handle, and apply pressure as you slide the trowel up. This will give the plaster a very smooth finish.

To protect your bench from the rain a coating of linseed oil should be applied. This will need to be done every two years.

Every part of cob is creative. This bench got a topping of tile around the upper edge.

Cob Bench

<<4^th Street and F Street>>

Patrick McAuley

ENGR 305 LAB

Fall 2003