How to repair different plaster cracks?

[johnk]

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 

[johnk]

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.

  

[MitchellMc]

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]

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

Roller was brand new from bunnings and intentionally 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]

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

Mitchell

[johnk]

ok thanks - does that roller look ok?

[MitchellMc]

That roller appears fine, @johnk.

Mitchell

[johnk]

This is also the response I received from Taubmans:

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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]

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