I have a concrete pond, the corners have been sealed with a black paint-on
substance, then a layer of what looks and feels like thick alu foil, then
more of the black stuff painted on.
The black stuff is very thin, more like a coat of paint than a rubberised
sealant.

Some of the foil type stuff has come away, I want to seal the corners in the
same manner. Problem is, I don't know what either the black substance or the
foil substance are.

Anyone know if this is standard stuff, or what?

Pete

"PM" wrote:

Hello PM

P I have a concrete pond, the corners have been sealed with a
P black paint-on substance, then a layer of what looks and
P feels like thick alu foil, then more of the black stuff
P painted on. The black stuff is very thin, more like a coat
P of paint than a rubberised sealant.
P Some of the foil type stuff has come away, I want to seal
P the corners in the same manner. Problem is, I don't know
P what either the black substance or the foil substance are.

P Anyone know if this is standard stuff, or what?

It'll be a tar based compound of some sort, probably bitumastic
emulsion (which is just like a paint). It's an excellent sealer and
retains some flexibility. I'd guess the foil is there as either a
proprietry system, or a form of protecting the inner layer.

If the leaks are fine cracks then it might work just painted over
again - but do ensure it's ultra clean and super dry.

TBH though, if it's been sealed then it suggests it's leaked before as
concrete ponds don't typically need to have further sealant other than
render, but some folks do so that's not a rule. It could be a symptom
of structural instability and it might never be fixable by patching.
OTOH, a butyl liner /will/ seal it perfectly...

--
Simon Avery, Dartmoor, UK Ý http://www.digdilem.org/

"Simon Avery" wrote in message
...
"PM" wrote:

Hello PM

P I have a concrete pond, the corners have been sealed with a
P black paint-on substance, then a layer of what looks and
P feels like thick alu foil, then more of the black stuff
P painted on. The black stuff is very thin, more like a coat
P of paint than a rubberised sealant.
P Some of the foil type stuff has come away, I want to seal
P the corners in the same manner. Problem is, I don't know
P what either the black substance or the foil substance are.

P Anyone know if this is standard stuff, or what?

It'll be a tar based compound of some sort, probably bitumastic
emulsion (which is just like a paint). It's an excellent sealer and
retains some flexibility. I'd guess the foil is there as either a
proprietry system, or a form of protecting the inner layer.

If the leaks are fine cracks then it might work just painted over
again - but do ensure it's ultra clean and super dry.

TBH though, if it's been sealed then it suggests it's leaked before as
concrete ponds don't typically need to have further sealant other than
render, but some folks do so that's not a rule. It could be a symptom
of structural instability and it might never be fixable by patching.
OTOH, a butyl liner /will/ seal it perfectly...

--
Simon Avery, Dartmoor, UK Ý http://www.digdilem.org/


Thanks Simon. Is bitumastic emulsion safe for fish/frogs etc? I'll give it a
google.
The only concrete sealant I've come across so far is PVA, and I don't know
whether this is suitable for ponds...

Pete

"PM" wrote:

Hello PM

P Thanks Simon. Is bitumastic emulsion safe for fish/frogs
P etc? I'll give it a google.

Yep. Or at least, I've used it myself with no problem - leaving a week
for it to cure. I've also used Silicon solution (proprietry
waterproofing fluid - WaterSeal, AquaSeal etc) and no mystery dead
fish because of that. Again, a week's good drying time.

But with your mystery black stuff, I think bitumastic is about the
only thing that'll stick to it. Chances are it's tar, or a dirivative
(like bitumastic).

P The only concrete sealant I've come across so far is PVA,
P and I don't know whether this is suitable for ponds...

Yep, another thing I've used extensively. Painted on to block, then
mixed with first coat of render (rendered block pond), two more
painted coats, mixed for final render, then two more painted coats.
PVA is great waterproofing, BUT it ain't a gap-filler really.

--
Simon Avery, Dartmoor, UK Ý http://www.digdilem.org/