6 x 6 backing block x 638 = 22,968 pounds. That would lift this
particular boat, almost two of them, in fact.

My real question was whether the stuff appears to grab with close to
its potential strength on old fiberglass.

I'd certainly lay up a nice epoxy and glass backing panel in this area
if I could reach it. If 5200 holds even 60% of its book number on the
ground fiberglass, it's probably plenty strong though.

--

Roger Long



"BF" wrote in message
...
3M lists tensile strength of 5200 as 638psi in salt water, Emerson &
Cuming
26 Eccobond GP Epoxy has an adhesive bond strength of 2100psi.
No personal experience but the numbers don't look appealing.
BF


"Roger Long" wrote in message
...
Does anyone have any direct experience with how well 5200 sticks to
old but cleaned up fiberglass?

I have to put a new backing block in for a through hull in a very
awkward location. Since it's a Signet Knotlog, it has to be flush
and
there isn't much back up in the taper for a direct hit on some
floating object. I'd like the back up block to be actually backing
it
up.

Building up with fiberglass and epoxy working through a hand sized
opening is going to be tough. I'm wondering if a larger than normal
sized plywood backing block done with 5200 might not be nearly as
strong.


--

Roger Long

As said, I have no personal experience. But my understanding is that 5200 is
a bedding / sealing compound, not an adhesive / bonding agent. Without
substantial testing or experience, I would be very leery.
My guess is that 3M will say the same. They will, however; be happy to talk
to you about your application. In my experience, they have been quite
cooperative in trying to help customers solve problems.
BF


"Roger Long" wrote in message
...
6 x 6 backing block x 638 = 22,968 pounds. That would lift this
particular boat, almost two of them, in fact.

My real question was whether the stuff appears to grab with close to
its potential strength on old fiberglass.

I'd certainly lay up a nice epoxy and glass backing panel in this area
if I could reach it. If 5200 holds even 60% of its book number on the
ground fiberglass, it's probably plenty strong though.

--

Roger Long



"BF" wrote in message
...
3M lists tensile strength of 5200 as 638psi in salt water, Emerson &
Cuming
26 Eccobond GP Epoxy has an adhesive bond strength of 2100psi.
No personal experience but the numbers don't look appealing.
BF


"Roger Long" wrote in message
...
Does anyone have any direct experience with how well 5200 sticks to
old but cleaned up fiberglass?

I have to put a new backing block in for a through hull in a very
awkward location. Since it's a Signet Knotlog, it has to be flush
and
there isn't much back up in the taper for a direct hit on some
floating object. I'd like the back up block to be actually backing
it
up.

Building up with fiberglass and epoxy working through a hand sized
opening is going to be tough. I'm wondering if a larger than normal
sized plywood backing block done with 5200 might not be nearly as
strong.


--

Roger Long

Well, I'm looking for some personal experience but thanks anyway.

The thing I have consistently heard about 5200 is that you shouldn't
use it on anything you hope to get apart again later.

--

Roger Long



"BF" wrote in message
...
As said, I have no personal experience. But my understanding is that
5200 is
a bedding / sealing compound, not an adhesive / bonding agent.
Without
substantial testing or experience, I would be very leery.
My guess is that 3M will say the same. They will, however; be happy
to talk
to you about your application. In my experience, they have been
quite
cooperative in trying to help customers solve problems.
BF


"Roger Long" wrote in message
...
6 x 6 backing block x 638 = 22,968 pounds. That would lift this
particular boat, almost two of them, in fact.

My real question was whether the stuff appears to grab with close
to
its potential strength on old fiberglass.

I'd certainly lay up a nice epoxy and glass backing panel in this
area
if I could reach it. If 5200 holds even 60% of its book number on
the
ground fiberglass, it's probably plenty strong though.

--

Roger Long



"BF" wrote in message
...
3M lists tensile strength of 5200 as 638psi in salt water,
Emerson &
Cuming
26 Eccobond GP Epoxy has an adhesive bond strength of 2100psi.
No personal experience but the numbers don't look appealing.
BF


"Roger Long" wrote in message
...
Does anyone have any direct experience with how well 5200 sticks
to
old but cleaned up fiberglass?

I have to put a new backing block in for a through hull in a
very
awkward location. Since it's a Signet Knotlog, it has to be
flush
and
there isn't much back up in the taper for a direct hit on some
floating object. I'd like the back up block to be actually
backing
it
up.

Building up with fiberglass and epoxy working through a hand
sized
opening is going to be tough. I'm wondering if a larger than
normal
sized plywood backing block done with 5200 might not be nearly
as
strong.


--

Roger Long

On Mon, 27 Mar 2006 22:35:18 +0000, Roger Long wrote:

Well, I'm looking for some personal experience but thanks anyway.

The thing I have consistently heard about 5200 is that you shouldn't
use it on anything you hope to get apart again later.

Sound advice.

Keep in mind it's used to glue decks onto hulls.

Matt O.

Absolutely right, I won't use 5200 to bed anything. I wanted to remove 2 old
Fuller brush portlights that were bedded with 5200 and ended up having to
cut them out in pieces with a sawzall.
5200 is a really good adhesive for a product that's not supposed to be an
adhesive!
MMC

"Matt O'Toole" wrote in message
news
On Mon, 27 Mar 2006 22:35:18 +0000, Roger Long wrote:

Well, I'm looking for some personal experience but thanks anyway.

The thing I have consistently heard about 5200 is that you shouldn't
use it on anything you hope to get apart again later.

Sound advice.

Keep in mind it's used to glue decks onto hulls.

Matt O.

Roger Long wrote:
Well, I'm looking for some personal experience but thanks anyway.

The thing I have consistently heard about 5200 is that you shouldn't
use it on anything you hope to get apart again later.

I used Sikaflex 241 (a close relative of 5200 with similar strength)
to bond some plywood to the hull. The plywood was a T joint into the
side of bare fiberglass hull. Just an edge glued fillet of the
Sikaflex on either side of the joint.

When I tried to later remove the stuff it just laughed at me. I had
to cut the plywood into 4" wide strips AND use a crowbar with feet
well braced to get the bond to break for each individual strip of
plywood.

5200 has a well deserved reputation for not letting go. Yes, it has a
low hardness but for your application it won't matter.

Evan Gatehouse

BF wrote:
As said, I have no personal experience. But my understanding is that 5200 is
a bedding / sealing compound, not an adhesive / bonding agent. Without
substantial testing or experience, I would be very leery.
My guess is that 3M will say the same. They will, however; be happy to talk
to you about your application. In my experience, they have been quite
cooperative in trying to help customers solve problems.
BF

You ever try to get that stuff off of anything. My cabin sole was glued
down with 5200. The bottom ply stayed glued to the floor. Had to use a
putty knife and hammer for about 10 hours to get it up. It is definitely
an adhesive/bonding agent. Use Lifecalk for bedding.
krj

Roger Long wrote:

6 x 6 backing block x 638 = 22,968 pounds. That would lift this
particular boat, almost two of them, in fact.

My real question was whether the stuff appears to grab with close to
its potential strength on old fiberglass.

I'd certainly lay up a nice epoxy and glass backing panel in this area
if I could reach it. If 5200 holds even 60% of its book number on the
ground fiberglass, it's probably plenty strong though.

Roger,
If you can sand the fiberglass surface then clean with mineral spirits,
5200 will stick. I have used it several places to bond things to the
hull during my boat refurbishing.
krj

mineral spirits is OIL, use acetone to clean the ground polyester/glass