Scrape off as much as you can and let it dry-out naturally, which could take a long time, before attempting to redecorate. I plan to use Macpherson powerkote, hopefully three coats to give it a strong finish. Do you think the powerkote will be suitable to use? When you have removed as much loose material as possible, treat the worst affected areas with a stabilising solution which will bind any reaming loose martial, presenting you with a solid surface on which to paint. Only do this on the very worst affected areas though. An algebraic Riccati equation is a type of nonlinear equation that arises in the context of infinite-horizon optimal control problems in continuous time or discrete time.

I have tried stabilising solution and PVA but the problem keeps recurring. Any suggestions to prevent this happening would be helpful. I am about to re-paint some stonework outside my house. It has previously been painted, but in areas it is a little flaky and kind of like white dust build up, think it’s salt or something like that.If this be the case then scrape off any loos paint, allow to dry out over a period of a few weeks and paint again. You may well find this is an ongoing process or it may be isolated to one or two problem areas. P = A T P A − ( A T P B ) ( R + B T P B ) − 1 ( B T P A ) + Q . {\displaystyle P=A

Dry and chalky areas can sometimes be primed with a watered down coat. But if the area has already been treated with a stabilising solution I would paint over this with unthinned masonry paint. Furthermore, the stabilising solution and PVA will both act to keep any moisture within the concrete, hence why you experiencing problems. The moisture will force its way out eventually. In such cases, I always recommend that the wall is left exposed to weather for at least 12 months prior to painting. For our situation it is a little too soon to tell the success of Lakeland’s stabilising solution on our bathroom problem wall area. This one wall area (a small cluster of patches) is particularly troublesome with a gradual peeling and bubbling appearance (under the painted surface) And this taking time to reappear once you cover with a fresh coat of paint. However what we have noticed is the Lakeland’s stabilising solution is not only pleasant and odourless —and oddly almost as transparent as tap water—and you're not sure if this only a water that you’re applying : ) However a noticeable difference is apparent once we painted over Lakeland's stabilising solution with white pigmented organic emulsion paint There seems to be a far more opaque surface quality that seems to suggest that not only is Lakeland's stabilising solution useful for troublesome unstable or damp patches on many types of wall surfaces but also this medium improves the colour density of the applied painted areas.For larger areas of filler I roughly smoothed over, then again used the paintbrush to texture and blend in the filler. Just scraping over with a knife will leave a smooth area which will show through the paint

Regular masonry paint is formulated to allow small levels of moisture to escape through evaporation. It’s important, therefore, to avoid the use of sealers or primers unless absolutely necessary. However, once it’s rubbed the surface below is relatively solid. I am worried that if I paint the surface with sandtex it could bubble if I don’t stabilise. Just bear in mind that the stabilising solution will impair the breathability of the finishing coats so only apply to areas where it’s really necessary. Would you ever used a watered down first coat on areas of render that are dry and chalky so have been treated with stabilising solution? Normally, masonry walls can be primed with a thinned solution of water-based masonry paint. But, sometimes, the surface can be loose and/or powdery and this can cause problems.

Funding

Below is a sample of questions received on the subject of stabilising primers… White dust on stonework? I would not normally advise painting since this is going to present yet another barrier to any trapped moisture evaporating away naturally without causing further damage. Allows painting of new render finishes and re-pointing repairs without alkaline contamination of the paint, which would otherwise delay painting by up to 2 months. Eventually I repainted with a water based masonry paint. Every year since then the paint has bubbled and I have had to scrape and repaint. Would you recommend the use of sandtex stabilising solution as a primer to prevent the paint failure??