What are "cemented down posts"?
You can purchase "sonotubes", cardboard tubes, at Lowes or Home Depot in the concrete department. They come in several different diameters. I forget what lengths they come in. The White House has rough posts? Aren't the posts "greek", smooth with grooves running from top to bottom. Not being funny, don't know and just asking. Billie

Here's the David-to-english translation:

Cemented down: I'm planning to take 10x4x4s, dig 3 food deep holes, drop them in and "cement them down". Then I'd have 7 feet of wooden beams that I'd probably want to dress, unless I go with straight up cedar.

Whitehouse like: I'd go with the limestone look recipe (high proportions of white portland cement and peat, lo proportions of very fine sand). If I go with the grooves, I'd probably take your concrete tube idea, and add 1 inch thick PVC pipes to the border to simulate the grooves. I'd probable have to find a way to seal them and prevent the tufa from going through.

I have been pondering other ideas as well, but I'd like to add this as one of the possibilities :-)

I've recently completed a "granite" post using a similar technique. I used a pressure treated 4X4 sheathed with builder's styrofoam attached with finish nails and craft glue. I textured the foam to create an irregular surface and then applied the mixture. I left the bottom 2 feet of the 4X4 exposed for setting into the ground. The results have been very satisfactory.

You must love your dog! This is a big project.
You might try using the cardboard tube (painted on the inside) around the wood posts. Fill from the top using a mix with sifted peatmoss and much more sand than you are planning plus strengthening fibers.
The grooves could be formed by half round wooden pieces fastened to the inside of the tube. The grooves could also be scraped into the column with a round nosed chisel and an indexing fixture of some sort.
It would be much easier to build up the columns in two foot sections, adding one tube on top of the previous one.
Caution!! Always think about how to remove the tube form without damage. The cardboard tube probably will have to be cut into three pieces lengthwise so it can be removed. Also be careful when adding the top of the arbor. You will need to keep out water from the inside of the tufa coating or freezing will ruin the columns.

Awesome advice Barny and Fred.

I like the rounded wood technique for the grooves, and I may just create 2 foot sections.

I still haven't made up my mind on what to do with the columns, but I do know there will be tufa involved.

Thanks!

Here is one of two columns that I made using sono tube and a couple other molds.
it is a project worth investing the time in. My columns are only about 2-3" thick, with a 4" pvc pipe down the middle.
Each finished column has about 18" of concrete into the ground to stabilize it.
happy casting.
Dena

[URL=http://home-and-garden.webshots.com/photo/1075285581034013916YHZuLa][IMG]http://thumb16.webshots.net/s/thumb1/8/55/81/75285581YHZuLa_th.jpg[/IMG][/URL]

Here is what the garden room looked like last year.
The columns have held up well.
[URL=http://home-and-garden.webshots.com/photo/1075285581034013916YHZuLa][IMG]http://thumb16.webshots.net/s/thumb1/8/55/81/75285581YHZuLa_th.jpg[/IMG][/URL]

Awesome job!

I'm all fired up

Here's the link for those of you who will have trouble with that uri:

Column image

If you're using the wood, the the styrofoam sheath is a good idea since wood will expand and contract and so could crack the hypertufa.

The peat in your mix will make an aged look quickly, more of an ancient Greek look than a Whitehouse one.

Dena or anyone----
could you make this column project more structural by using the 4x4 post in the center. Daisy above mentioned wood expanding and contracting. Would that only happen if the 4x4 was sunk into the ground at the base -
I am wondering if you could make a post for a deck, using 4x4 posts- but before you install the decking, take a tube and create a hypertufa column outside. Thus having the support of the 4x4 but the exterior of the hypertufa -
Would this work

Hi, I can't give you any suggestions on the columns but I'm a long-time (30 years) dog breeder and am going to suggest that you buy a good sturdy crate for your dog. Think of it as giving her a room of her own. It will make a great deal of difference for the better in everyone's life! It is unfair to expect a dog to know that you find certain things precious and therefore "off limits" for behavior that is as natural as walking to her.If she is safe in her own room you can certainly take the liberty to chose your projects with a different criteria than saving your furniture.
spiderwoman