Hi all

Is there such a thing as "the best" silicone for sealing a gap in
masonry?

The specific application is: we have a step to the porch. The pointing
at the point where the step meets the porch's brickwork has a thin crack
all the way along it (movement of the step I presume). This permits
water (when it's raining hard) to seep down behind the step, which then
wets the brickwork (which is above the DPC), and consequently we have
florescence(?) on those bricks when the sun gets out.

I figure on chipping out the pointing and replacing it with a silicone
bead (possibly applying a thin layer of mortar on top of the bead for
appearance's sake).

is there a reliable silicone for this job? It seems to me that when
silicone first appeared in tubes, it was magnificent stuff. In recent
years there seem to be dozens of different brands and types of
"silicone", some of which to my certain knowledge dissolves in water.

Cheers
John

Another John wrote:
[snip]
is there a reliable silicone for this job? It seems to me that when

No.

silicone first appeared in tubes, it was magnificent stuff. In recent
years there seem to be dozens of different brands and types of
"silicone", some of which to my certain knowledge dissolves in water.

I suspect that you will find that the silicone that dissolves on water
isn't silicone. It will be a sealant but is likely to be acrylic, not
silicone.

For the use that you intend, I would use polysulphide sealant, not
silicone. A good alternative is polyurethane sealant such as Sikaflex.