Easifill sanding issue

[daggermark]

I've used Easifill 45 a lot over the years but having a problem with sanding it flat on a particular wall.

Had a fairly large patch (6" x maybe 1') of blown paint on a wall, so got the 10" taping knife and Easifill out to patch it flat. I'm not too fussy about feathering because usually this stuff sands flat in seconds, but I didn't leave it hugely proud of the surface either.

However, this time I've had a big problem sanding it flat with the existing and I'm not sure why. The wall was otherwise sound, free from dust and grease. When I sand the edge, the filler just strips once it gets down to a certain level. I can get it very close to flat, with an edge just about detectable by touch or with a work-light angled onto it. But then when I try to sand that last little bit it just strips off the wall so I'm back to a noticeable step. I'm using p120 alu oxide paper.

Any ideas? Seems like poor adhesion between the filler and existing painted wall (matt emulsion, also sanded a little and cleaned prior to filling), but I'm not sure why?

 

[opps]

Have you tried 180 or 220g paper?

It does sound like poor adhesion. Was it still in date, mixed properly, was there too much suction in the substrate?

I guess you could seal it and then feather it wit another filler.

 

[daggermark]

Filler was new-ish and well mixed yes.

I think suction could be an issue.

In the end I sealed the whole lot over with gardz and re-filled the 'step' with some of that ronseal pre-mix rubbish I had lying around. It ended up good enough for now, although I wonder how long it will last!