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Penetrating Sealant

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mick H12/05/2021 08:34:11
766 forum posts
28 photos

Can anyone assist me with a penetrating sealant that will be effective in the following circumstance?

A model outline "submarine" where the 4inch diameter wooden bow section slots into a 4inch diameter drainage pipe. The joint is screwed and then sealed with a rubberised gasket sealant and was a sound waterproof joint when created. I then "plated" the hull with shim brass sections fixed with epoxy resin. I thought that this would result in a belt and braces waterproof seal. After further work on the boat a flotation test has revealed a small leak in the joint and from the amount of water entering I guess would probably amount to no more than a pinhole. An attempt at stopping the leak on the inside with more rubberised gasket predictably met with failure.

In conclusion, somewhere on the lower hemisphere of the joint mating surface circumference there is a tiny leak which has to be retro-sealed as dismantling the joint is no longer an option. The question is how? Any ideas on an effective penetrating sealant?


Edited By mick H on 12/05/2021 08:35:17

MichaelR12/05/2021 09:08:21
466 forum posts
74 photos

You could try a very low viscosity Super Glue which will wick into the leaking area, of course the offending area will have to be well cleaned of other sealant.


MichaelR12/05/2021 09:08:22
466 forum posts
74 photos

You could try a very low viscosity Super Glue which will wick into the leaking area, of course the offending area will have to be well cleaned of other sealant.


Another double post ?

Edited By MichaelR on 12/05/2021 09:08:59

mgnbuk12/05/2021 09:15:08
1176 forum posts
71 photos

Captain Tolley

Captain Tolley's Creeping Crack Cure is a longstanding recommendation in motorhome circles for sealing "hard to find" leaks. Might work here ?

Nigel B.

Brian H12/05/2021 09:37:09
2312 forum posts
112 photos

Plus 1 for Captain Tolley. Also useful for boats and showers etc, as long as the surfaces can remain dry before immersion.


Nigel Graham 212/05/2021 10:42:46
2036 forum posts
28 photos

You might find a problem with water trapped within the very leak you are trying to seal, so the compound would have to be water-repellent or able to adhere in water.

Might be worth contacting the makers of the candidate sealants for their advice on that, if it's not clear in their sales descriptions.

duncan webster12/05/2021 13:11:02
3928 forum posts
61 photos

If you can dream up a way of applying some vacuum to the inside of the sub it will pull sealant into the pinhole

Tim Rowe 112/05/2021 13:30:52
14 forum posts

+ 3 for Captain Tolley's Creeping Crack Cure to give it its full name.

It is a low viscosity acrylic compound that cures in the presence of moisture. It will tolerate some moisture in the crack it is sealing. If there is a crack it will "wick" in instantly. When it won't wick anymore the joint / crack is full. Sometimes it needs 2 or 3 goes and works better for that rather than trying to do in in one hit.

When cured it remains flexible so is idea when sealing different material and where expansion and contraction are involved.

I would be lost without always having a bottle in the cupboard.

Tim R

mick H12/05/2021 16:52:56
766 forum posts
28 photos

Thank you for your advice gents. I did try creeping crack cure and failed. I now know why and Nigel has mentioned it above. Obviously there was water still trapped within the joint! If I had read Captain Tolley's advice it may well have been successful. I will have to leave it in the sun to dry out which it eventually must do, surely. Not sure how to apply a vacuum Duncan but will think about it. Perhaps a little high pressure air might force it out but again not as easy as it sounds.


Dave Halford12/05/2021 18:15:22
2007 forum posts
23 photos

Valve from an old pushbike inner tube. if you paint the outside of the model with washing up liquid it should blow bubbles from the leak / leaks and blow the water out at the same time.

That way you get to fix it from both sides.

Edited By Dave Halford on 12/05/2021 18:15:48

noel shelley12/05/2021 18:19:15
1284 forum posts
21 photos

CT1 ! will work on wet surfaces, abit like silcone but it is not and more expensive at about £13 a cartridge. It has a high bond strength so it's a good adhesive. once open IF kept properly sealed it will keep for 2 years and still be useable. Good luck, Noel.

Bazyle12/05/2021 19:27:29
6297 forum posts
222 photos

It may be too late to make modifications but the original soil pipe submarine featured in Model Boats in the '70s sealed the end of the tube with two aluminium discs with a slight chamfer around the periphery to form a groove for an O-ring bolts. Pulling the two discs together with bolts pushed the O-ring out to form the seal making the pipe a sealed compartment and leaving the ends to free flood.
For my first sub before seeing that high tech solution (way beyond my equipment to produce) I used glaziers putty. Sticks to everything. Made getting the hatch off a real mess.

Dave Smith 1412/05/2021 21:24:08
212 forum posts
43 photos

A std household vacuum cleaner will produce prodigious suction and can be used to create a vacuum. We used to use them at work to do deflection tests on aircraft structures due to suction at around 1.5 to 2.0 psi. You need to use the air bleed near the attachments mount to bleed air to prevent the part collapsing.

John Haine13/05/2021 06:50:11
4630 forum posts
273 photos

Ronseal wet rot treatment.

John Haine13/05/2021 06:50:32
4630 forum posts
273 photos

Ronseal wet rot treatment.

John Haine13/05/2021 06:50:37
4630 forum posts
273 photos

Ronseal wet rot treatment.

mick H18/05/2021 06:28:01
766 forum posts
28 photos

Three cheers for Captain Tolley and his Creeping Crack Cure. It works a treat if you follow the instructions (even if it does sound a bit like a rear end medicament). I left the boat to dry out and applied the cure to every minute crevice I could find. A few applications and a couple of days drying out and the boat is now sound. Thanks everyone for your interest.


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