I always knew epoxy to be binary so the two components only need each
other to harden and are not affected by air or water. I see many
products marketed as epoxy which are only one component. And further
some of them admonish against wetness. Particularly for sealing
leaking basement wall cracks, which even a blow torch after acid could
not dry. What gives?

--
Vasos Panagiotopoulos panix.com/~vjp2/vasos.htm
---{Nothing herein constitutes advice. Everything fully disclaimed.}---

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On 11/6/2023 8:16 AM, vjp2.at@at.BioStrategist.dot.dot.com wrote:

I always knew epoxy to be binary so the two components only need each other to harden and are not affected by air or water. I see many
products marketed as epoxy which are only one component. And further
some of them admonish against wetness. Particularly for sealing
leaking basement wall cracks, which even a blow torch after acid could
not dry. What gives?

There are those like J-B weld with one component which is actually two
part and are kneaded to mix. I read there are also premixes that need temperature to activate. Best adhesion is when there is no boundary
layer and maybe water can act like that and boundary layer must be removed.

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On 06/11/2023 13:16, vjp2.at@at.BioStrategist.dot.dot.com wrote:

I always knew epoxy to be binary so the two components only need each other to harden and are not affected by air or water. I see many
products marketed as epoxy which are only one component. And further

Cite?

Quite a few epoxy products these days like epoxy putty are still a two
part system but physically separated in concentric cylinders rather than
two tubes. You cut a bit off and mix it well to start it curing.

People were forever putting the wrong lid on each tube so the marketing
men came up with "simpler" to use alternatives at a higher price. The
dual syringe is another solution which also ensures the mix ratio is
right - that is another way Joe public screw up using epoxy.

some of them admonish against wetness. Particularly for sealing
leaking basement wall cracks, which even a blow torch after acid could
not dry. What gives?

Epoxy won't stick to wet or greasy surfaces. There are high tack space
filling polyurethane glues that will though. Some of them require you to
wet the surface being glued first to enhance the curing reaction.

I think you are confused. It doesn't help now that there are daft
brandnames around that don't immediately translate into chemistry.
"Gorilla glue" being one such example.

ISTR it started out as a high tack PU glue and then diverged. https://uk.gorillaglue.com/gorilla-glue-original/

--
Martin Brown

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On 11/9/2023 11:15 AM, Martin Brown wrote:

On 06/11/2023 13:16, vjp2.at@at.BioStrategist.dot.dot.com wrote:

    I always knew epoxy to be binary so the two components only need each >> other to harden and are not affected by air or water. I see many
products marketed as epoxy which are only one component. And further

Cite?

Quite a few epoxy products these days like epoxy putty are still a two
part system but physically separated in concentric cylinders rather than
two tubes. You cut a bit off and mix it well to start it curing.

People were forever putting the wrong lid on each tube so the marketing
men came up with "simpler" to use alternatives at a higher price. The
dual syringe is another solution which also ensures the mix ratio is
right - that is another way Joe public screw up using epoxy.

some of them admonish against wetness. Particularly for sealing
leaking basement wall cracks, which even a blow torch after acid could
not dry. What gives?

Epoxy won't stick to wet or greasy surfaces. There are high tack space filling polyurethane glues that will though. Some of them require you to
wet the surface being glued first to enhance the curing reaction.

I think you are confused. It doesn't help now that there are daft
brandnames around that don't immediately translate into chemistry.
"Gorilla glue" being one such example.

ISTR it started out as a high tack PU glue and then diverged. https://uk.gorillaglue.com/gorilla-glue-original/

Gorilla Glue does have other products that are not urethane's. There is
even a tape. Other name brands do this as I believe Sevin is no longer
the original insecticide.

One thing that irritates me as a chemist is the plastic bottle of
Gorilla Glue has a finite lifetime before it hardens. The bottle looks
like polyethylene which is one of the most permeable plastics to water.
I find it much better to buy it in the mini metal tubes they sell.

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