Mending Cornicing

[Nina]

Hi. I have been a regular browser of this forum for some time and have found it very helpful in dealing with certain aspects of our massive renovation of our Georgian townhouse, as well as enjoying the banter of regular contributors. I have a question which maybe someone can help me with. I am cleaning our very clogged-up cornicing in our sitting room, which is painstaking work as the detail has been totally hidden by layers of paint. Some of this will be impossible to save due to years of water damage above the window and down one wall (and this will have to be remade in a traditional manner by a local firm), but most of it is looking fine. Some small parts are coming away and I was wondering what sort of adhesive I would need to use to stick this back up. The only bits that are loose are some of the patterned, leafy looking bits, the cornicing above and below is OK (if that makes sense).
Thanks in advance for any advice.

Nina

 

[Penners]

Nina - welcome to the forum.

I've never done the job that you mention, but I seem to remember others posting some time ago that plaster of paris is effective for sticking loose bits of plaster cornice back into position.

Hopefully more experienced folk will confirm or deny this.

 

[chuckey]

From memory, plaster of paris is sloppy for say 3 minutes, then stiffens up then goes rock hard in 10 seconds. i.e. its very difficult to use as a glue unless the part is fuly supported in position. I also suspect that the "3 minutes"(above) shortens to 30 seconds if the parts you are fixing suck any water out of the mix. It also occupies space so you can't get a minmal glue line.
Well, thats all very negative!, I would be tempted to try "super glue" (breath on the edges being glued first, the glue needs dampness) or EVA (waterproof PVA) glue, which needs to be supported.
Let us know what you do and any snags you have found, I'm sure others will be interested in your experience.
Frank

 

[Penners]

Despite what I said above, I do tend to agree with Frank - provided the surfaces to be joined show a clean break, with no lost material or gaps to be filled.

 

[Nina]

Thanks to both of you for responding. I also think that anything potentially really messy (or sloppy) will cause me major problems as I am up a ladder, half balanced against a high wall and doing a sort of juggling act. I feel anything that is going to be unusable in a matter of seconds/a minute will get me in a panic, possibly covered in gluey stuff, and on the floor with most of the cornicing on top of me. Everything is very fiddly. I think I might try the EVA glue first .... I have enough dodgy cornicing to practice on.


Nina

 

[Pford75]

If it's just a couple of small pieces of 'detail' (and assuming that you cannot hold them in place whilst a plaster mix dries), I would even suggest araldite or some other 2 part adhesive. It's not in any way a 'period' repair, but it should be invisible and does have the added advantage of being tacky very quickly, but still workable. Since it isn't water based, it will also not suffer from the water being 'sucked' into the plaster too quickly.

 

[AMc]

I also think that anything potentially really messy (or sloppy) will cause me major problems as I am up a ladder, half balanced against a high wall and doing a sort of juggling act.

Superglue can be very good stuff and really does "bond skin in seconds" :shock: . That wasn't an issue when I did it fixing my kid's toy at my desk - 2 minutes of work with a craft knife and I had full use of my finger and thumb again - hand glued to the top of a ladder might be a different story

I would seriously consider buying/hiring a more suitable working platform than risking a serious injury or bodging the repair for ever more. Just a suggestion to keep you out of Grahams Top Tips thread

 

[Feltwell]

I think EVA wood glue has to be worth a try if as Penners points out there's no gap filling required.

Believe it or not you can use it to put coping back on with! Sounds like a terrible bodge but it works a treat, on cement mortar at least. I knocked a couple of bricks off the top of a (built with cement mortar by a previous owner) low retaining wall round my patio, whilst moving a scaffold tower. Rather than chipping the mortar off and re-bedding them, a bit of waterproof wood glue spread liberally on both sides worked a treat and gave an "invisible" repair as all the original mortar remained. 2 years later and they are still stuck fast.

Not exactly "period" and don't do this for anything structural though!

 

[Nigel Watts]

I did quite a bit of this kind of restoration work a few years ago. I found that a mix of strong Plaster of Paris (eg Herculite) and lime putty to be quite effective as an adhesive. The lime putty gives substance to the otherwise very sloppy plaster.

If you want to try this, here are a few tips:

1. make sure that the Plaster is at least 50% of the mix
2. wet both surfaces thoroughly before applying, to reduce suction
3. the mix goes off in a few minutes, but its worth waiting a little bit for it to go slightly cheesy before trying to marry the two parts up (this increases the chance it will stick and not fall off)
4. hold the piece in place for 30 seconds or so before letting go
5. if you dont get the mix right it can fail, so be prepared for it to drop (have something soft for it to fall onto just in case)

A final suggestion. If you are going to get some repairs done it may be better not to stick all the loose bits back as one of them may be needed to form a mould. My cornices (c. 1840 early Victorian) were made of a combination of straight lengths which would have been run in situ, rosettes which were stuck to the ceiling and moulded sections stuck either to the ceiling or top of the wall (or both, as below). These sections were about six inches long and clearly made offsite and then stuck in place. I had to make copies of some of these rosettes and moulded sections- something that is much easier to do if they are not stuck in place. Making copies of the hollow sectioned piece in the photo below was especially challenging, and would have been next to impossible without taking a section down first.

For small bits which have just snapped off a modern glue is better as it is less bulky. I found UHU quite effective.

Good luck!

 

[Penners]

Hi Nigel - I hoped that you would respond to Nina's thread. I reckon you've probably done more of this type of repair than the rest of us put together!

 

[fjpdesigns]

Another method you could consider is one I use for mending plaster figurines, although I've never had recourse to try it on cornicing.
Using PVA. Water down some pva till it resembles thin milk and give both surfaces and surrounding area a good soaking. You can use small paint brush for this. Let it dry overnight, then repeat with a second coat.If this doesn't soak in then just wipe off the excess and allow to dry. This will seal the plaster. The following day use full strength pva to glue the pieces together.Wipe any excess off with a damp rag. You may need to support the mend whilst it's drying. You can do this with sellotape, rubber bands, anything that will comes to hand.
If it's a big piece to glue back then I would suggest drilling some holes through the loose piece ( while it's correctly positioned) into the back plaster and glueing some galvanised wire of almost the same diameter into the holes using pva again. Do all this final gluing at the same time. Remember these holes will need a soaking in the watered down stuff along with the rest of the area. You must be careful to cut the wire slightly shorter than the depth of the hole, then fill in the hole with plaster or that polyf......( I don't think I dare write that), and smooth when dry. You should achieve a much cleaner and neater repair this way than using plaster if you are not used to using it.
I have found araldite and superglue peel off the plaster too easily as it's such a dry surface.
Happy mending.

 

[Nina]

Thank you all for your helpful tips. Today our builders were back to mend the ceiling which is sagging in places and is a huge threat to my precious cornicing. The chunks that have already come off are about 6 to 8 inches long but most of it is looking preety secure at the moment. With reference to Nigel's thread, I was planning to keep these long bits that cannot be put back up (due to damp damage mentioned earlier) and clean them up at ground level, so to speak, and give them to the guys who will be making me the new plaster cornicing so that they can copy it exactly in a much easier manner than if it was in situ. The whole cleaning operation is/will take me an age as I am working and seem to be doing this in fits and starts. Anyway, you have all given me good ideas. I wait to ensure that I still have a ceiling to work around.....


Nina

 

[Pford75]

Nina - Glad the various responses have been helpful...as Penners says, Nigel has done a lot of this sort of work.

Well, best of luck and if you ever get chance to post some photos, we'd love to see how it's going

 

[Penners]

Hear, hear! We shall demand photos of the finished work! :wink:

 

[Nina]

You may have to wait an age for pictures of the finished product. I have just come down from my ladder and have bits of cleaned cornicing, numbered and in a box (like museum exhibits), awaiting the moment of re-adhering. I'm hoping all the heavy work regarding the fireplace is not going to damage the recently finished ceiling and cornicing downstairs in the dining room.... I am seeing suspicious hairline cracks wherever I look and am no longer sure if they are new or have always been there.... talk about paranoia.

 

[Nigel Watts]

Nina

Haired lime plaster is pretty robust and can take quite a bit of crashing about on the floor above (I have two young boys who do a lot of crashing about and my ceilings are still in place). Problems start when the nibs break (the excess plaster which squeezes between the laths and holds the whole thing up). Some of my ceilings were quite fragile in some areas. I had these parts strengthened by screwing a number of recessed bolts with large square washers into the joists. The surveyor tested the strength of different parts of the ceiling by gently pressing it and seeing how much give there was - the more give the greater likelihood that it is parting company with the laths.

Have you thought yet how you might decorate the cornice when it is finished? Having spent many hours up ladders getting a crick in the neck cleaning all the gunk off I could not bring myself to slapping on a modern emulsion paint which would be next to impossible for any future restorer to remove. I concluded that the most friendly (and most authentic) way would be to use a water based distemper. This could relatively easily be washed off in future. Distemper also has a wonderful matt finish which is far superior to modern vinyl emulsion. You can even make it yourself if you are so inclined.

In cleaning my cornices I was intruiged to find traces of earlier colour schemes. We so often assume these days that ceilings and cornices (not to mention interior and exterior woodwork) should be painted white that it can come as quite a surprise to discover how colourful earlier schemes were. In my living room the cornices appear originally to have been distempered in an oaky colour, no doubt to match the trompe l'oeil fake oak wallpaper of which I found traces (and which someone at the V&A said could date from the 1840s, when my house was built) and to match the oak-grained woodwork. Although I have not recreated the wallpaper - I have used a dark green damask design instead - I have reproduced the oak-grained woodwork and oak coloured distemper. The effect is authentic early Victirian gloom; very un-Islington, but I like it.

The first floor bedroom, whose cornice is shown in the above picture and which I did first, seems originally to have been coloured in a combination of pale blue and pinky orange. I took photos, but at the time I did not have the courage to go with this (no original wallpaper here), so I ended up using white distemper and dark blue paint on the walls. My neighbour who has a mirror image semi but with different cornice designs also found that her cornices had been multicoloured when having them cleaned. They are now all covered up with several layers of white Dulux. Maybe when I comes to redecorating I will do something more ambitious!

Nigel

 

[Nina]

Good morning, Nigel.
Our builders have also dealt with the problem ceiling in the same manner as you (ie screwing bolt things in) and the difference in sagginess is really surprising. I have already cleaned and painted the downstairs dining room cornicing (much simpler cornicing consisting only of straight lines) and I used a white distemper which looks great ...soft and rather powdery, like icing sugar... luckily there is only very little modern paint on these cornicings so that cleaning it is delicate and time consuming but not likely to cause damage as the stuff on it comes away relatively easily. Your cornicing is wonderfully ornate, mine in comparision is much simpler. I have not found the different colours that you have.We have lost the cornicing above the window due to death watch in the lintel. We had this beetle quite badly especially in the joists and the huge oak beams (whole trees!) in the roof. Also wet rot that I thought was some strange white insulation product when I first set eyes on it...I despair at my own ignorance sometimes. The years of damp on one side of the house caused by exposure to the elements (we sit on the old city wall) has caused lots of problems .... but we have wonderful views.

 

[Cloudscape]

The years of damp on one side of the house caused by exposure to the elements... has caused lots of problems .... but we have wonderful views.

I had to laugh at that. It sounds like us. The house is a freezing-cold bombsite with 1000 jobs that needs doing... but it's a lovely area to live in. :lol:

 

[hoppy]

Nina,
Originally youe "Enrichment would have been fixed using plaster of paris (Fine casting plaster).
We still fix enrichments in the same way,however casting plaster starts setting in 4 minutes, If you have more than you can fix in this amount of time i would recommend you use "Fibrefix". We use Fibrefix to fix complete rooms of cornice as the setting time is approx 1 hour.

hope this helps
PDS (listing in fibrous plaster section)

 

[Nina]

Just an update on my cornicing fixing problem. I tried a couple of the suggestions given me. I found the plaster of paris very difficult to work with. One moment it was too sloppy and made a mess everywhere, the next it was too solid to work with. I had to work very quickly which was not possible when the cornice bits were small and fiddley. Superglue worked but not at awkward angles .... I was too busy trying not to get it on my fingers. In fact the best result came from the araldite ... easy to use, gave me time to get the broken cornice in exactly the right place (so no joining line could be seen) and has stuck fast. The only drawback was holding it in place while it adhered.....serious arm ache. The result is very good. We are waiting for a long length to be made for us (as previously stated, lost through chronic water damage). I 'remade' small bits that had crumbled away with a soft clay/plaster mix that I bought from an art shop in a tube. Once dry and hard, I distempered it and it looks good.
Thanks again for the advice.