What to do with crack in the ceiling - now filled but i cant sand it flat

[platforminc]

Hello.

We have had an extension and major works 2 years ago, got a crack line running across the ceiling, it was about 3 - 4m long, one was 3m long and the other 4m long. I filled it last year and sanded It but I think my filler mixing was bad, the filling doesn't stick and after a few days starts to fatten out and eventually cracks and breaks out, also I suspect there are beams around the area. One of the cracks definitely has a beam around the area, the other doesn't but has a sky lantern opening within close proximity.

This time i decided to do things differently.

I am using ready mix filler (interior and exterior).
Tried to open the crack so it's a little bigger and form a V shape with the cut opening let's say 2p coin and slightly bigger in some places.
Applied a bit of SBR Pva prior to filling.
Applied sticky fibre tape (orange colour ) across the length of the crack, cut the tape into 2, say 20mm covering.

What is the issue now ?


The filler is rock hard, I cant sand it by hand and make I flat. Then when I read the tub, I said internal and external use.

I have used a detail sander and 40 grit sand paper. Not much is coming off to get a flat surface before painting and not damage the filling with thr intensity. To make things worse, the joint fibre paint is orange in colour and therefore is quite obvious with filler on It even though I have tried to use filler to cover the tape. Too much filler means you get a bump.

I'm confident the cracks will.no longer show up, however to make it look good. I need to sand it further before painting. What tools can I use apart from a detail sander or what should i do in the situation ?

 

[DiyNutJob]

Skim it.

 

[platforminc]

Can't do that. Will I have to skim the entire ceiling. Quite a size. I'm not confident in doing that.

 

[Mr Chibs]

I would have used something like a hand operated Mirka sander, linked to the hoover, go lightly with a medium grade mesh.
If linked to the hoover it will make a lot less dust.

Mirka Sander

What filler did you use... I used Toupret filler for both in and out... it sands nice.

I hate sanding ceilings and as mentioned skimming is probably the final answer.

 

[JohnD]

Try a broad metal scraper, and shave it off.

Of course you should have done that before it hardened.

 

[DiyNutJob]

Will I have to skim the entire ceiling.

You don't. You only need to skim over the non-flat surface. A curved ceiling surface is indistinguishable from a flat ceiling.

 

[platforminc]

Can I use an orbital sander with say 120 grit do the trick ?

 

[DiyNutJob]

Because the filler is harder than the surrounding, you will end up taking off material in the surrounding creating a dip there.

 

[platforminc]

Because the filler is harder than the surrounding, you will end up taking off material in the surrounding creating a dip there.

Ooh dear.
I'm just looking for the easiest way out. If I were to skim it, will this be done with multifinish and is the idea to loose the non flat area into the rest of the ceiling to create a gentle bump ?

What tools /materials will I need ?

 

[DiyNutJob]

You need jointing compound and a special "putty knife" that is very wide - maybe 8 inch. Because the stuff is easy to sand you could just use a normal putty knife and then sand. The goal will be to have a gentle blending of the stuck out filler with the surrounding using the compound.

 

[platforminc]

I have the 8 inch putty knife. Can you please send me examples of the jointing compound, when I Google it u can see easi fill 20 and Co. Not sure which is the best one and is ready mix better or powder ?

Do I also need a plastic float ? I have a wide knife thing with its own handle and its like 200mm wide. I guess timing is key with the skimming, shape up before it sets ? Would it be wise to cover from left to right over the line or over the line from one end of the line to the other on the long side ?

 

[DiyNutJob]

You can go in any direction you want. But I suggest you go slow and do a 1 foot long section along the filled crack to get used to it. You don't want to be making a huge mess while you learn. If the "putty knife" is very flexible then that's all you need.

Powder is more convenient and you can mix as little as you need:

British Gypsum Gyproc Joint Filler 12.5kg | Wickes.co.uk

British Gypsum Gyproc Joint Filler 12.5kg

www.wickes.co.uk

 

[sparkwright]

What filler did you use?

And can you scrape it off, and basically start again with something a bit more sandable?