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How to repair different plaster cracks?

Hi all,

Have 4 types of cracks that I am wanting to repair in my home all in plaster whilst I paint my house. The house is 25 years old and these cracks have just slowly expanded over the years and have never been repaired as such, so quite good for 25 years.

1. Hairline cracks in ceiling - these are extremely fine but run for a number of meters - was thinking to either run the edge of a paint scrapper inside the crack to expand it and fill with Uni Pro Multi Purpose - then simply paint and not even bother using an undercoat as I am painting the entire ceiling and walls. Alternative was to use tube of acrylic gap filler and simply use my finger to fill in and paint over.

2. Corner tape edge has peeled off in one of the corners - was going to use mesh tape and then several thin layers of Uni Pro Multi Purposed Filler to evenly spread this out - 2 -3 multi purpose filler coats sanded in between - and then simply paint over with the same paint I will use for the walls and ceiling

3. Some larger cracks over my timber venetian blind areas - I can see some mesh tape there - was going to sand, add some additional mesh tape and fill in with Uni Pro Multi Purposed Filler to evenly spread this out - 2 -3 coats sanded - and then simply paint over. Was also considering to not add any mesh tape but simply run the edge of a sharp plaster blade to expand and then simply fill in and sand.

4. Some cracks where the wall meets the ceiling and there is timber trim - was simply going to use a tube of acrylic gap filler

and a caulking gun to fill this in.

Pics attached and look forward to any advice!

Thank you.

John.Corner tape peeiling offHairline Ceiling crackLarger crack over blindsCracks where ceiling meets wall

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Comments

EricL

Hello @johnk

Thanks for sharing your question about the interior cracks in your plaster. You would get better results with the Uni Pro Multi Purpose filler on your ceiling as it will cure to a plaster like consistency and will not sink or settle. Whereas the acrylic gap filler might sag or move while it cures. For the corner edge you might need more filler, and I suggest using Gyprock CSR 2.25kg Less Mess Multi-Purpose Joint Compound specially if you are removing the old mesh tape in the corner. You can use the joint compound on the large cracks near the blinds and your idea of using an acrylic gap filler for the wall and ceiling will work just fine.

Here is a link to our best advice: How do you repair ceiling cracks?

Here is a handy step-by-step guide: How to repair a cracked cornice

I also suggest having a look at this discussion - How to repair cracks on the wall, celling and cornice? by @mmd22.

If you have any other questions we can help with, please let us know.

Eric

johnk

https://www.workshop.bunnings.com.au/discussion/comment/42217#Comment_42217

Thanks Eric,

does the Gyprock multi-purpose-joint-compound then an additional compound on top of it as a finishing compound?

Also with the ceiling crack, is my idea to make the crack bigger with the edge of a plaster tool the right approach before filling in?

Ta.

John.

EricL

https://www.workshop.bunnings.com.au/discussion/comment/83240#Comment_83240

Hi @johnk

Technically the multi-purpose joint compound will add a layer to finishing compound, but the properties of the multi-purpose compound allow you to get a fine finish on its surface when sanded properly. In regards to making the crack bigger, it is a sound step as it removes all the loose parts of the crack and allows more of the filling product to enter the crack and thereby allowing it to grab onto the sides of the crack.

If you need further assistance, please let us know.

Eric

johnk

https://www.workshop.bunnings.com.au/discussion/comment/106491#Comment_106491

Thanks Eric,

What about the option of a quick setting compound so I can fill, sand and paint within a few hours? Any recommendations?

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/120438#Comment_120438

Hi @johnk,

The Poly 100g Rapid Interior Filler is a great multi-purpose fast-setting filler. Painting over can be completed in 30 minutes, so you should be able to sand quite soon after application, depending on the temperature and humidity.

Mitchell

johnk

https://www.workshop.bunnings.com.au/discussion/comment/129036#Comment_129036

So a bit of an update.

Wall repairs proceeded well although I found the rapid set plaster difficult to work with as it’s very plastic and soft.

After 2 coats of Taubmans Easy Cost paint the issue I have that the ceiling looks quite blotchy in appearance and despite sanding it very smooth somewhat rough. Wondering if I needed to have diluted the paint as it was warm and humid upstairs when I applied this? Will try and post some pics but wonder now if I should fine sand and apply a final 3rd coat but that is diluted with water as this paint seems quite porous.

Advice would be appreciated.

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/134576#Comment_134576

Some images would be beneficial in providing advice @johnk. Provided the filler was sanded smooth, there shouldn't be any blotchiness after coating, nor should there be any reason to dilute it.

Keen to assist further.

Mitchell

johnk

https://www.workshop.bunnings.com.au/discussion/comment/138045#Comment_138045

hi @MitchellMc,

See the images attached. This is why I am thinking of a light re-sand with 220 grit and also applying a final coat when it is a lot cooler to avoid the paint going really sticky when I apply it. I am also considering adding something like Floetrol to the paint which is a paint conditioner that help with paint spread and better flow.

I suspect that I did not get the same effect on the walls as they were cooler and the ceiling in these photos is on the second level which can get very warm.

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/140406#Comment_140406

How much of the ceiling did you cover with the Poly 100g Rapid Interior Filler, @johnk? Typically, it is used for smaller repairs, and to skim-coat a whole ceiling, you'd use a topping compound.

The ceiling has quite a rough and gritty texture. Was that introduced by the Rapid filler, or was it rough to begin with?

Mitchell

johnk

https://www.workshop.bunnings.com.au/discussion/comment/142115#Comment_142115

I only used the Rapid filler on a very small strip, and on a few other sections I used the Uni Pro Multi Purpose filler. See images.

The surface of the ceiling was nice and smooth before I applied the paint, sanded with 220 grit and also cleaned with a damp microfibre pad.

The roughness you see I think is because the paint was very gluggy when I applied it and very sticky as I see it.

IMG_2831[1].JPG IMG_2833[1].JPG

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/143339#Comment_143339

Thanks for clarifying @johnk.

What kind of roller did you use? Typically, we'd use one with a 12mm nap on a ceiling. I'm asking because I've never really seen roughness like this introduced due to temperatures.

It sounds like you're on the right track and a sanding is required to knock down the peaks on this roughness.

I'd question why the paint is gluggy or sticky. It should be thicker than water but should flow quite easily. Was it an older can that you've had sitting around, and whether it is new or old, did you give it a mix before starting? If it's a new can, I'd be inclined to take it back to the store of purchase and show them the images. At a minimum, they can shake the can for you to ensure it's mixed correctly, or they might have some other ideas as to how this roughness has been introduced.

Mitchell

johnk

https://www.workshop.bunnings.com.au/discussion/comment/144249#Comment_144249

Intentionally bought smaller quantities of paint and all tins were brand new.

Roller was brand new from bunnings and intentionally IMG_2854[1].JPG IMG_2855[1].JPG went for an extra wide roller - 30 cm.

Will pop into a store later today and get some advice - is the trade desk generally the best place to speak to someone?

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/144920#Comment_144920

No, see the team at the paint desk @johnk; they're the Experts on painting projects.

Mitchell

johnk

https://www.workshop.bunnings.com.au/discussion/comment/145448#Comment_145448

ok thanks - does that roller look ok?

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/145858#Comment_145858

That roller appears fine, @johnk.

Mitchell

johnk

https://www.workshop.bunnings.com.au/discussion/comment/146175#Comment_146175

This is also the response I received from Taubmans:

----------------------------

Hello John,

There is both flashing and lapping visible and it is being highlighted by glancing light in the photos supplied.

Flashing is where patches of uneven sheen level or texture appear. Also recognised as: • Gaps • Patches • Patchy • Shades • Shading • Shiny • Streaks • Streaky • Uneven sheen.

This is caused by painting over areas that are dry or have begun to dry (loss of ‘wet edge’) e.g. overlapping fresh paint with paint that has already begun to set. • Swift air circulation and porous surfaces also affects the wet edge time and can induce this effect if painting too slow. In the photos provided it appears you have used a Low Sheen finish instead of a preferred ceiling paint. This will also accentuate the appearance of lapping.

Flashing can be prevented by applying even coats of paint. Perhaps by using larger brushes / rollers, that can cover more area in less time and prevent the loss of ‘wet edge’. Avoid the need to ‘go back and touch up’ areas. Work in good light but work away from the light. Ensure, wherever possible, that material from same batches are used to touch up. Where flashing has occurred, an additional wet coat applied under good drying conditions will usually remedy the problem. Alternatively, you could add a paint conditioner like Flood Floetrol which can aid in retarding the paints wet edge time.

Lapping is the appearance of a denser colour or increased gloss where the wet and dry layers overlap during paint application.

Maintain a wet edge when painting by applying paint toward the unpainted area and then back into the just-painted surface. This technique (brushing or rolling from 'wet to dry,' rather than vice versa) will produce a smooth, uniform appearance. It is also wise to work in manageable-size areas and plan for interruptions at a natural break, such as a window, door, joint or corner.

Glancing light describes lighting that shines across the paint at an acute angle and casts shadows across the surface and highlights surface irregularities. Using a Matt Ceiling Paint can help reduce the irregular appearance across the ceiling.

To rectify, we recommend giving the surface a light sand to smooth any irregularities across the surface. Wipe down and remove any sanding or dust particles and allow to dry. You may need to consider using Flood Floetrol using the mixing instructions on the pack to slow down the drying and to maintain the wet edge of the paint film. Apply another coat keeping the wet edge and using a bigger roller 270mm – 360mm to cover larger surface area and allow to dry. As mentioned we also recommend the use of 2 topcoats of Taubmans Easy Coat Ceiling paint to help reduce the effect on the ceiling.

JacobZ

https://www.workshop.bunnings.com.au/discussion/comment/146442#Comment_146442

Hi @johnk,

Seems like some good advice from the team at Taubmans, thank you for sharing.

These Rocket 230mm Giant Sanding Tools work with most paint extension poles and are a great way to reduce the load on your body from sanding a ceiling. This Rocket Giant Sander Sanding Sheets - 6 Pack contains 2 x 240 grit sanding pads that would be perfect for this job.

As per Taubmans' advice, you can also add some Flood Floetrol to your paint to slow down the drying time. Ensure you follow the instructions on the label for mixing ratios.

Let me know if you have any further questions.

Jacob

johnk

https://www.workshop.bunnings.com.au/discussion/comment/146655#Comment_146655

So after completing this project in lat November, things have held up well.

For the corner cracks, I used a mesh and then multiple coats of UNi-PRO 500g Multi Purpose Interior Filler. I then sanded and shaped this again and again over several days. If you are doing these type of repairs DO NOT use products like Selleys 180g Spakfilla Rapid Gap Filler. Products like this simply cannot be shaped and sanded! I am not sure I would recommend this product for anything other than maybe a small tiny hole needing to be repaied in a hurry!

By biggest boo boo was putting on the first coat of paint on the ceiling on a very warm day. I have then learned that the best approach is to choose a cool or cold day to do this to be able to spread the paint out evenly and so it does not texture. I then had to get a proper ceiling paint, do some re-sanding, a paint spreading chemical, and apply multiple coats to even things out. There are still some small blotches but it's hardly visible.

For the ceiling cracks, I did not use any mesh. I simply sanded flat the ceiling area, and filled in with by finger and a small spatula the cracks - sure the cracks might re-appear in the fure, but they took 25 years to be created so I'll simply fill them in again in 25 years!

I took the opportunity also to fill gaps between all the windows and walls with a flexible tube of filler and then paint over this. This has created a nice finish and there is less creaking sounds coming from the windows due to temeprature changes. Did a similar thing with some of the timber trims from the kitchen that hit the wall. Sealed these multiple times over several days to get a nice finish. There were 18 of them!

For the ceiling down lights, I chose not to remove these. There were more than From previous experience, removing the fixtures will crack the plaster. I chose to mask tape these. After removing the masking tape, I used a very small model painting type brush, to add some additional ceiling paint around them. The result is excellent.

It all took 2 weeks and cost something like $600 mostly due to my mistake with the ceiling painting and doing multiple additional coats. This is for about a 60 square meter living space (not sure what the painting area is but I would guess the ceiling is 60 square meters and the walls are also at least that as well).

Overall, have a new appreciation for people who paint ceilings. It is back breaking work! and sure I know that many people use sprays etc, but this is not always possible!

Corenr repairedWindow sealed - looks better in real lifeCracked wall repairesPainted CeilingPainted Ceiling

EricL

https://www.workshop.bunnings.com.au/discussion/comment/146853#Comment_146853

Hello @johnk

Thank you so much for the photo update. Your repair work looks fantastic!

Eric

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