about over-application of sealants & glues

[Bob Blarney]

Hello,

I'm dealing with a previously described leak of the Penguin air conditioner condensation/rain drain, at the connection between the drain pan and discharge hose connector. There was big glob of caulk smeared around and on the connector and drain pan, and yet water was infiltrating past it and dripping.

I noticed this before but haven't mentioned it, that sealants and glues seem to be more cohesive than adhesive, i.e. it sticks to itself better than the surface that needs to be sealed. As before, it appeared to me that that the solvent and plasticizers had gradually evaporated, and the caulk had shrunk and contracted, and pulled away from the surface. Considering that there is very little water pressure on this joint (an inch or two of water at most), a thick glob was unnecessary and just made things more difficult in the end. Proper surface preparation and a thin layer are all that's really needed.

So I cut and peeled the glob away and cleaned the surface. At the moment, the only sealant I have is Lexel (Sashco mfr), and so I applied a thin layer around the fitting and tiny cracks, and smoothed it over. I think it will work ok, considering that there is very low pressure, and if it doesn't, then it won't be difficult to remove it, and maybe try Captain Tolley's Creeping Crack Sealer. I'll let you know if the Lexel doesn't work.

[Hittenstiehl]

Good to know.

This would also be good to post in the sealants summary thread.

[KK4YZ]

Following

[ROBERT CROSS]

I cleaned ALL the surface factory 'goop'. Re-sealed the mating curbs and screw threads and heads with 3m marine sealant, and covered with 3m Extreme Sealing tape.

Bob
🇺🇸

[SYC2Vette]

I had a cargo trailer that developed a leak around the roof seam. It had a large amount of sealant extending away from the joints, but you could lift it in large pieces with no bond to the aluminum. So yes it is all about surface prep including a good primer perhaps.

[dznf0g]

Less, (properly and carefully applied) is more....

[harryk]

Why not replace the hose ?

[guskmg]

Be careful using alcohol as a cleaner. Some sealants are incomparable with it. Carburetor cleaner is better.
guskmg

[Wazbro]

Originally Posted by harryk

Why not replace the hose ?

It's quite difficult to feed a new hose between the skins from the AC to the bottom of the trailer.

[Rhinno]

I had a similar leak and a similar gob of separated sealant. On closer inspection, I found the plastic itself had hairline cracks. I cleaned it well, checked that the plastic was dissolved by acetone (styrene) and used acetone to soften the crack areas a sacrificial piece of styrene to strengthen it. No caulking/ sealants. Ugly, but better (stronger) than new.

[doughpat]

Originally Posted by guskmg

Be careful using alcohol as a cleaner. Some sealants are incomparable with it. Carburetor cleaner is better.
guskmg

Assuming one allows substantial time between cleaning and application of the new sealant, isn't it safe to assume the alcohol will have evaporated completely?