Ornamental Wall Copings

[Manxmodder]

I have need to renew a couple of ornamental cement wall copings in the near future.

The existing ones being around 100 years old are badly frost damaged,cracked with peices missing and well beyond patching up repairs.

These type of copings were originally formed by with a profiled template being run back and forth on timber guide rails,very much the same method as used to produce ornamental plaster cornice mouldings.

I am after some info on best methods and techniques to accomplish this task,has anyone here any pointers as to where I may get some relevant books or anything on the internet?

I know I could pre-cast the profiled coping in fibreglass moulds in metre lengths and set them onto the wall but this method is always obvious that the coping was produced in sections and does not have the authentic appearance I wish to achieve.
Thanks in advance for any useful info that may be offered.....OZ. 

[Manxmodder]

I've just found this youtube vid that is the most detailed info I have come across yet.
What I am looking to do is very similar to this technique but the forming is all done in situ on top of the wall itself.
Link to vid(fascinating stuff) https://youtu.be/5h4cb0HMV-E
OZ.

[awemawson]

I've done it in plaster but never cement, though I doubt it's much different.

You fix a lath below for the 'horse' to slide along. The horse is two bits of short plank fixed in a tee shape. The upright of the tee has the approximate shape you want but a bit larger. Then a zinc sheet is fixed to it with the exact shape. Plaster is pressed into the corner and the horse slid along to form the coving. It's an iterative process.

[Manxmodder]

Thanks,Andrew  . I'm familiar with the 'horse support(can be made from 10mm ply) and the thin metal profile needing to be slightly smaller.

I also just found this vid of another Filipino runing a moulding in situ on a window sill. The common thing in both vids being they seem to use a finer slurry mix with less aggregate as they get out to the final coats.

Also notice that both vids show the guy dusting with cement in between layers to stiffen the stuff already laid up.

I'm thinking it may be a good idea to set up a dummy wall top made from some pieces of scrap plywood with a bit of expamet mesh and have a bit of experimentation on that to get a feel for the process.

I also feel that when I come to do the real thing that it would be advantageous to add some reinforcing glass fibres to the undercoats to deter any cracking......OZ. 

Window sill moulding video : https://youtu.be/8WZNF-Mlfk0

[edward]

In plaster I recall my now late grandfather making the zinc templates to match existing cornice by painting the existing one with olive oil (no idea if extra virgin or not ) and applying Plaster of Paris as a mass. Once set, remove and saw through the middle of the plaster profile to give a flat piece with the profile, then scribe round it onto zinc and cut with snips.

this was what got attached to any formers etc to run the new cornice. IIRC it was roughed out with plaster and scrim, then a finer paste used with the profile for finish.

All subject to the memory of an 8 year old at his grandads knee, but might be useful info.

[awemawson]

I was once helping a friend fit a cistern in the loft of his newly acquired ex-Rectory, and we found the horses neatly stacked for all the coving in the house - house is mid 1800's.

He didn't realise how lucky he was.

[chipenter]

In redering the surface is finnished as the cement sets and is still green , 3 to 5 hours depending on the strength and temp , a cross grained wooden float was used origonaly but a resin one is used nowa days to rub off and change the finish .

[SwarfnStuff]

Just watched the videos and I wonder what the men's hands are like after a day of sprinkling raw cement with them? Still, very interesting to watch them gradually build up the profile and then the finished article.
John B