Here is the question....... Why would 3M5200 bond fail?
I called 3M tech people and they sent Tech Data Sheet (effective:
12/1/2004). Interesting data.
I also called Royal Adhesive and received data for Silaprene.
This is what I read.
Stainless to Stainless Overlap Sheer Strength
3M5200.........352 psi
Silaprene......488 psi
Interesting.
What about temperature. I was painting my garage last summer. Ambient
temp was 94 degrees F. I hung a thermometer on the side of the garage
in direct sun. Temp of garage wall was 150 degrees F. OUCH!
How hot do chainplates and decks get in many parts of the world during
the hot season? 130-150-180F? Just a guess. How does temperature effect
plate adhesive bond? I got more TDS stuff.
3M data: (Service temperature -40F to 190F) "Heat resistance-Due to
the decreased value in bond strength at elevated temperature, we do not
recommend use of this product above 190F."
Silaprene data: (Service temperature -60F to 250F) " Heat
resistance-No significant loss of bond strength until 300 degrees F."
Elevated Temperature Shear Strength
3M5200......................(70F 240psi)(150F 176psi)(190F 139psi)Teak
test substrate.
Silaprene.............(70F - 250F)No significant shear strength loss.
Question. Could 5200 fail because deck and plate temperatures reduce
its bond strength?
Has anybody used Silaprene?
Comparing data each company supplied says Silaprene has greater bond
strength than 5200 on stainless steel and keeps its strength at
temperatures when 5200 begins acting like butter (exaggeration).
Ideas about the deck temperatures causing 5200 failure
Should I use Silaprene to rebed my chainplates "forever?"
Bob
Hasn't anyone tried a hot air gun and a putty knife?
Roger
der...@NOSPAMearthlinkNOSPAM.net
http://home.earthlink.net/~derbyrm
"bob" <cbo...@eou.edu> wrote in message
news:1126915291.8...@f14g2000cwb.googlegroups.com...
<snip>
> 3M data: (Service temperature -40F to 190F) "Heat resistance-Due to
> the decreased value in bond strength at elevated temperature, we do not
> recommend use of this product above 190F."
> Elevated Temperature Shear Strength
"bob" <cbo...@eou.edu> wrote in message
news:1126915291.8...@f14g2000cwb.googlegroups.com...
What error did you make and what were the problems?
You got to the center of my question..... why do we need to
rebed/calk/seal every 4 years?
Is it possible do it once every 20 years if the "proper " product is
used?
In other words, it sounds as though you used 5200 in the past as a
selant and it failed. SO why did 5200 fail?
Chris
"bob" <cbo...@eou.edu> wrote in message
news:1127426311.0...@o13g2000cwo.googlegroups.com...
Thanks for the reply. 3'x5' chain plates? Must be a big rig?!?
I'm not looking for an argument here. Just trying to muck my way
through boatbuilding tradition. I'm sure you've found in a few
insistences that the reason it is the "best way" is because they have
always did it that way. Time marches on and so do innovations. I may
very well find myself going with a polysulfide. But.....
However, I am hoping there is something "better" than polysulfide and
5200. My big question is: why does 5200 fail? You mentioned that it
does not take a squish very well. I know that 5200 can not handle temps
over 150 well. 3Ms data says 5200 can elongate 1300% with out
failure. So the pull in a gap should not be the problem. May the
problem is in the pinch?
Why do you say that 5200 can not take a squish? Is it damaged and lose
the bond??
Have you ever heard of Silaprene or used it?
Still in search
Hi,
Are you talking about bedding chainplates on the outside of a hull or
sealing where they pass through a deck?
For bedding I'd use eg 5200, mold release wax and some sort of spacers
to create a gasket, then seal the gasket and bolts holes/threads with
a sticky non setting compound.
I'd expect most problems occur where something is used to bed stuff
which is then tightened down too much initially, leaving a layer that
is too thin to take any movement and cannot be compressed further.
cheers,
Pete.
Excellent question.......... plates measure 1/2"x 2 1/2"x 20" and pass
through deck. Deck is cored: 1/4" glass, 3/4" end grain balsa, 1/4"
glass.
Plan on digging core out and potting with thickended epoxy. But still
confused about the next step: 5200 or ? to fill 1/4" gap between plate
and epoxy.
>
> For bedding I'd use eg 5200, mold release wax and some sort of spacers
> to create a gasket, then seal the gasket and bolts holes/threads with
> a sticky non setting compound.
Hummm. I like the sound of that.
The above is for plates bolted to a hull?
So suggestions for plates through deck?
> I'd expect most problems occur where something is used to bed stuff
> which is then tightened down too much initially, leaving a layer that
> is too thin to take any movement and cannot be compressed further.
Agreed. This is exactly what I have found with all other through deck
bolts. Big problem.
Things were alot easier when all I had to do was pour hot tar around
the hatch/deck channel. Not exactly yachat standards. But worked fine
til the next offload.
Thanks for the rply Pete,
BOb
>
> cheers,
> Pete.
>> Are you talking about bedding chainplates on the outside of a hull or
>> sealing where they pass through a deck?
>
>Excellent question.......... plates measure 1/2"x 2 1/2"x 20" and pass
>through deck. Deck is cored: 1/4" glass, 3/4" end grain balsa, 1/4"
>glass.
>
>Plan on digging core out and potting with thickended epoxy. But still
>confused about the next step: 5200 or ? to fill 1/4" gap between plate
>and epoxy.
>>
>> For bedding I'd use eg 5200, mold release wax and some sort of spacers
>> to create a gasket, then seal the gasket and bolts holes/threads with
>> a sticky non setting compound.
>
>Hummm. I like the sound of that.
>The above is for plates bolted to a hull?
>So suggestions for plates through deck?
Maybe something more flexible like Sikaflex 221/291 or equivalent
would be better than 5200.
For best leak proofing I'd use a 1/4" deep seam of 22l on the bottom,
then some round section 5/16" closed cell foam wound round the chain
plate combined with a generous amount of sticky butyl sealant, then
another 1/4 seam of 221 on the top.
Would be a little tricky, probably best to mask the top 1/4 of the
gap, put some foam in, do the bottom and wait for it to set, then add
more foam and non setting goo, pull the masking tape away and do the
top.
Still it would give 3 layers of sealing, even if the 221 failed in
part it would keep the other stuff in place nicely. Even if it did
need redoing in some remote place, it should be easy to cut through
the top and reuse the foam with more goo.
>> I'd expect most problems occur where something is used to bed stuff
>> which is then tightened down too much initially, leaving a layer that
>> is too thin to take any movement and cannot be compressed further.
>
>Agreed. This is exactly what I have found with all other through deck
>bolts. Big problem.
If making a gasket as above I'd use washers round the bolts as
spacers, then when they are removed I'd fill the hole with some non
setting sealant so it forms a nice donut round the bolt thread.
cheers,
Pete.