removing 4200/handrail

[anaisdog]

put my portlights in with 795 and those seem to be holding without leaks (YAY!) but now, my long handrail, starboard side, which i bedded with TONS of 3m 4200, 5 years ago is leaking in two places.  how do i get the thing off, without breaking it?  is there a 4200 remover or can I use alcohol without hurting the top of the boat?  i do have butyl to rebed it.  is there any wood/fiberglass preparation i need to do before switching material?  sand the wood?  thanks in advance

(do boats ever get dry???)

becki kain

[KWKloeber]

Google 3M 4200 remover -- there's 89,600 hits.

No doubt engineer overkill (Noah!!), but when I rebed mine I will seal the mating surface of the teak with a thin coat of penetrating epoxy (on bare wood), like Mas low-viscosity resin. 

Others' mileage may vary.

How did you handle the screw holes?
Pics??!?!?!

kk

put my portlights in with 795 and those seem to be holding without leaks (YAY!) but now, my long handrail, starboard side, which i bedded with TONS of 3m 4200, 5 years ago is leaking in two places.  how do i get the thing off, without breaking it?  is there a 4200 remover or can I use alcohol without hurting the top of the boat?  i do have butyl to rebed it.  is there any wood/fiberglass preparation i need to do before switching material?  sand the wood?  thanks in advance

(do boats ever get dry???)

becki kain

[Noah]

Becki- you might try this spray for removal:
https://www.debondcorporation.com

After unfastening, spraying this and letting it soak, use a non-flexible putty knife and carefully pry/slice under each bonding point, working down the entire length of the rail.

[anaisdog]

thanks. 

[anaisdog]

thanks Ken but i was hoping to not have to buy something special, just asking what else can be used.

[anaisdog]

and is butyl tape strong enough for a handrail, to bed it, instead of 4200?

[Noah]

Yes BT will work. The handrail bedding is NOT for intended for strength, or as an adhesive/glue, just waterproofing. The bolts are what supplies the holding strength.

[KWKloeber]

and is butyl tape strong enough for a handrail, to bed it, instead of 4200?

Uhhhhhhh......  the 4200 job is leaking, right? That answers the question. LOL.

BE SURE in the future not to use an adhesive product (especially a polyurethane or other type, that are terribly tenacious) where you want a caulk/sealant. And vice versa.

[KWKloeber]

thanks Ken but i was hoping to not have to buy something special, just asking what else can be used.

Not have to use something special    On a BOAT?????  Nah, that's wishful thinking. 3M planned it that way.  😂

[anaisdog]

screw holes?  you mean on the plexi?  nothing yet, i took the screws out since the 795 is cured and just put (disco) duck tape on them for now.  IF it ever stops raining in michigan, i will break out more 795 and fill them in.

and the yard would use 4200 on my handrails. i just talked to them.

[KWKloeber]

4200!?!?!?!  find a new source of recommendations.

As my M.I.L says, "just because they do it for a living, doesn't mean they are good at it."

Yeah the plexi holes,  795 is moisture cured.  LOL

k

screw holes?  you mean on the plexi?  nothing yet, i took the screws out since the 795 is cured and just put (disco) duck tape on them for now.  IF it ever stops raining in michigan, i will break out more 795 and fill them in.

and the yard would use 4200 on my handrails. i just talked to them.

[anaisdog]

i dont see why 795 would make you laugh out loud.  it is what catalina stated to use.  why is that funny?

[KWKloeber]

IF it ever stops raining in michigan, i will break out more 795 and fill them in.

795 is MOISTURE cured.  Get it???
It's ok. it's late. It's Friday. ;-)

[J_Sail]

Sorry this is long, but I couldn't figure out how to shorten it much...

Caulk fails when it either loses grip on one of the surfaces (called adhesive failure) or tears apart internally (cohesive failure). The typical cause of either failure is motion at the joint that exceeds the limit for the particular caulk/substrate combo. Most sealants can handle no more than about 100-200% stretch before either pulling away or tearing apart. If you make a caulk softer and more stretchy you reduce the amount of tension it puts on the adhesive joint. So, very soft caulks may not need to have as strong an adhesive grip (but can suffer physical damage if exposed). Firmer caulks need more adhesive power.

BUT... no matter what, you are unlikely to create a sealed joint that can repeatedly handle more than 100% stretch without failing.* That may seem like a lot, but if the thickness of the caulk inside the joint is only a few thousandths of an inch thick, then even the slightest motion will eventually spell doom. That's why MaineSail and other experts recommend putting a chamfer/bevel on the bolt/screw holes where they enter the fiberglass, using a countersink bit. That way there is a ring of caulk around where the bolt enters the hole (hidden by the teak rail) that's thick enough to provide a bit of motion without exceeding the limits of the caulk.
https://marinehowto.com/bed-it-tape/

Jeremy

* You will see ads for much greater degrees of stretch, but that's typically only for cohesive failure. In most real-life scenarios, adhesive failure will occur well before then.

[KWKloeber]

Excellent excellent description of the failures - becki, you are sealing all thru fastener holes using the epoxy/redrill method and doing the countersinking?  If that was done the 4200 shouldn't have failed. 

Ken

Sorry this is long, but I couldn't figure out how to shorten it much...

Caulk fails when it either loses grip on one of the surfaces (called adhesive failure) or tears apart internally (cohesive failure). The typical cause of either failure is motion at the joint that exceeds the limit for the particular caulk/substrate combo. Most sealants can handle no more than about 100-200% stretch before either pulling away or tearing apart. If you make a caulk softer and more stretchy you reduce the amount of tension it puts on the adhesive joint. So, very soft caulks may not need to have as strong an adhesive grip (but can suffer physical damage if exposed). Firmer caulks need more adhesive power.

BUT... no matter what, you are unlikely to create a sealed joint that can repeatedly handle more than 100% stretch without failing.* That may seem like a lot, but if the thickness of the caulk inside the joint is only a few thousandths of an inch thick, then even the slightest motion will eventually spell doom. That's why MaineSail and other experts recommend putting a chamfer/bevel on the bolt/screw holes where they enter the fiberglass, using a countersink bit. That way there is a ring of caulk around where the bolt enters the hole (hidden by the teak rail) that's thick enough to provide a bit of motion without exceeding the limits of the caulk.
https://marinehowto.com/bed-it-tape/

Jeremy

* You will see ads for much greater degrees of stretch, but that's typically only for cohesive failure. In most real-life scenarios, adhesive failure will occur well before then.