Interested in understanding how I approach crack repairs?
I first decide whether it is necessary to open the crack up. Is it level and structurally sound? Or is it just surface dirt sitting along the crevasse? Even when being extremely careful you can easily lose tiny fibres when opening and cleaning a crack, so I always try to keep the invasion to a minimum.
The photos are all examples where the look of cracks, a center joint and other messy areas have been improved just by cleaning the top surface, filling, scraping, and retouching. Same approach, same method, and the same materials every time.
1. I run a sharp knife along the dirt sitting in the crack, breaking the surface
2. I wash out the surface dirt with a soft brush using fairly hot water
3. Once clean and dry, I fill the crevasse with filler varnish (I use thickened semi-gloss Deft of honey consistency)
4. After a couple or more days, I scrape the Deft flat and then replicate the texture either side of it with my scraper (scraping along grain lines or craquelure for example)
5. I retouch the area
I know this is just scratching the surface of this complex subject and an overview, but this is my approach to dealing with cracks that are structurally sound and level.