internal corners on cornice

[cflake]

Does anyone have any hints after you have stuffed all your mitre joins and have to "fix" your internal corners after installing cornice? I've (unfortunately) ended up with some pretty embarrasing gaps.

[Groggy]

Cornice cement is your friend :wink: . Just fill the gaps and sand smooth till it is level and even. Amazing what you can hide really.

[cflake]

I'm assuming it's going to be difficult to sand an internal corner with a curved surface... I was hoping there was some magic trick that you could use.. like throw some top coat in there and use some sort of corner tool (like a wall internal corner) and taadaa!!

[rod@plasterbrok]

Really the best method it to cut (scrape) back the exess with a plasterers small tool and refill them. They will be easier to cut back as the new cement is setting. Use a wet sponge to soften the cornice adhesive and clean away any exess.

It is not the easiest of processes once it is mucked up, even a lot of plasterers dont seem to get it right.

There is no magic fix and you are quite right sanding in a corner like that is not easy.

Cornice is cheap you could take it down and re cut new cornice with mitres that fit.

See here http://www.how2plaster.com/bcc.html

Replacing it might be the way to go if it is too hard for you to fix. If you cut it right and measure and place it right all you really need to do is wipe out the corner with a wet sponge to get a reasonable job.

Cheers

Rod

[Dirty Doogie]

LOL Cflake - if only there was such a tool !! But there is a tool called - um - a "small" tool - yeh I'm sure that is what it is called. http://www.abc.net.au/sydney/stories/s1055643.htm

These are great for stuffed up corners. I fill the big gaps with cornice cement but make sure the surface of the cement is well back from the the finished edges - then carefully sculpt the profile again with topping compound. some small pieces of sandpaper are also helpful.

the process will bring out the (sculpture) artiste in you.

[rod@plasterbrok]

Be careful if you use topping compound on a mitre. Cornice Adhesive is designed to be able to cut back smoothly as it is going off and brushed or sponged to smooth finish. Top coat like mud shrinks and cracks if it is applied in any thick form such as filling a mitre.


Cheers Rod

[Dirty Doogie]

Yeh big lumps of topping will crack. I use 4T formula 1 from the usa which IMO beats other local made topping compounds in terms of workability, drying and sanding. Generally I only have to fill 2 - 3 mm over the cornice cement which seems to work pretty well.

I have found that if cornice cement - even just smears of it on the cornice profile - sets, it is very hard to sand off and shows through paint.

[Tools]

It will be easier to repair one side first, following the profile of the cornice, and then once it has hardened, do the other said. This will avoid you gouging out the opposing surface.

Tools

[rod@plasterbrok]

It all comes back to measuring, cutting and putting it up properly then none of these problems exist.

It is really simple to do, there are just a few key points that make it or break it. The most common problem is not keeping the saw upright when cutting the cornice. This tends to "hollow" out the mitre giving you a mitre that requires fill from both sides.

The cornice must be held in profile while cutting with the saw upright. Pushing down too hard on the saw will also cause problems, let the say do the work.

See the other tips on my site in the above link.

Cheers Rod

[vlv8vic]

Ah cornice. Not sure how many times i nearly killed myself after seeing what i had done to a perfectly good piece of cornice. I crappy cheap cornice mitre box made all the difference. I used lots of bog and lots of fiddly sanding in the first few attempts. Renovation learning curve is steep.