On Saturday, 10 October 2020 11:41:30 UTC+1, Dave Plowman (News) wrote:
In article ,
newshound wrote:
On 09/10/2020 14:25, Dave Plowman (News) wrote:
A fixing into a plastered brick wall through tiles.

Most of the fixings went well - wall plugs pushed through the tiles into
the brick. But one obviously hit the soft old mortar, and won't tighten.

Anything that could be squirted through the hole to give a decent fixing?
Or any other ideas? I'm already at the limit of the longest screws I can
find in that diameter.

It depends a bit on whether you have a blind hole or whether you have
gone into a void of any significant size. Polyester resin is one of the
classic "fixes" for this sort of problem, but perhaps a bit expensive
for just the one, and a small hole. Also, how strong does the fixing
have to be?

If probing suggests you have a reasonably small blind hole, it's just
that the plastic plug is spinning, then one strategy would be to inject
a surplus of epoxy glue, then push in the plug and wait for it all to
set. Make sure the plug is all the way through the tile. If the void is
larger but still fillable could you inject in mixed up car body filler
to fill it completely? Forget the wall plug, just drill a pilot hole and
let the screw grip on the filler.

Snag is due to the uneven plaster, I used dot and dab for the tiles.
Meaning there is very likely a void between the tile and hole in the
brick. It's approx 35mm from the outside of the tile to the bricks.

Some form of syringe with a long needle would allow me to inject gunge
into where the wall plug is - but where to get one that long?

If you really mean you've got 35mm from tile to brick, I'd just bung filler in & redrill. The filler creates solid sides for your new hole, which you can then fill as needed.