Pierre,

What chemicals are you talking about?

Regards, Ron

(Ron Thornton) wrote in message ...
Pierre,

What chemicals are you talking about?

Regards, Ron

With the microwave idea, I would not apply enough power to turn the
water to steam, but enough to heat it to cause evaporation from the
strips where the gelcoat has been peeled. This would cause the water
from furhter from the strips to migrate (with the dissolved chemicals)
to the peeled strips. Perhaps after the hull had dried enough, you
might peel another inch on either side of the strips to get rid of
more of the chemicals. HOWEVER, I am doubtful of ANY process getting
rid of enouigh of these chemicals to matter since these chemicals are
part of the resin holding the fibreglas together. The best bet may be
to either not worry about blisters or to get rid of the water and then
encapsulate the hull in a membrane that will not allow water
penetration. Once again, has anyone heard of any real hull failures
from osmotic blisters?

The uncured resins that are really the basis of blisters don't hold the
fiberglass together. They have to be heated to temperatures higher than the
boiling point of water to get rid of. This can be a problem with cored
hulls, where you might actually reach the glass transition temperature of
the coring material before you get rid of the uncured resins. It's a common
misconception that it's just water in the hull. It's really the acidic
non-cured resins (which are hydroscopic in nature). See:
http://www.hotvac.com/
http://www.daviscoltd.com/nams/Docum...er_Report.html
http://www.yachtsurvey.com/blisters.htm
http://www.marinesurvey.com/yacht/BlisterRepairFail.htm
http://www.osmosisinfo.com/

....to learn more about blistering, it's causes and repairs.


"Parallax" wrote in message
om...
(Ron Thornton) wrote in message
...
Pierre,

What chemicals are you talking about?

Regards, Ron

With the microwave idea, I would not apply enough power to turn the
water to steam, but enough to heat it to cause evaporation from the
strips where the gelcoat has been peeled. This would cause the water
from furhter from the strips to migrate (with the dissolved chemicals)
to the peeled strips. Perhaps after the hull had dried enough, you
might peel another inch on either side of the strips to get rid of
more of the chemicals. HOWEVER, I am doubtful of ANY process getting
rid of enouigh of these chemicals to matter since these chemicals are
part of the resin holding the fibreglas together. The best bet may be
to either not worry about blisters or to get rid of the water and then
encapsulate the hull in a membrane that will not allow water
penetration. Once again, has anyone heard of any real hull failures
from osmotic blisters?

Thanks Keith,

That explains a lot.

Regards, Ron

"Keith" wrote in message ...
The uncured resins that are really the basis of blisters don't hold the
fiberglass together. They have to be heated to temperatures higher than the
boiling point of water to get rid of. This can be a problem with cored
hulls, where you might actually reach the glass transition temperature of
the coring material before you get rid of the uncured resins. It's a common
misconception that it's just water in the hull. It's really the acidic
non-cured resins (which are hydroscopic in nature). See:
http://www.hotvac.com/
http://www.daviscoltd.com/nams/Docum...er_Report.html
http://www.yachtsurvey.com/blisters.htm
http://www.marinesurvey.com/yacht/BlisterRepairFail.htm
http://www.osmosisinfo.com/

...to learn more about blistering, it's causes and repairs.


"Parallax" wrote in message
om...
(Ron Thornton) wrote in message
...
Pierre,

What chemicals are you talking about?

Regards, Ron

With the microwave idea, I would not apply enough power to turn the
water to steam, but enough to heat it to cause evaporation from the
strips where the gelcoat has been peeled. This would cause the water
from furhter from the strips to migrate (with the dissolved chemicals)
to the peeled strips. Perhaps after the hull had dried enough, you
might peel another inch on either side of the strips to get rid of
more of the chemicals. HOWEVER, I am doubtful of ANY process getting
rid of enouigh of these chemicals to matter since these chemicals are
part of the resin holding the fibreglas together. The best bet may be
to either not worry about blisters or to get rid of the water and then
encapsulate the hull in a membrane that will not allow water
penetration. Once again, has anyone heard of any real hull failures
from osmotic blisters?


It seems that most blisters occur between the gelcoat and "skincoat"
of fibreglas or betwen the skincoat and the actual structural matting.
In most cases they have no effect on structural strength since the
skin coat is only there to prevent "print through" of the underlying
matting that does provide structure. These blisters are almost always
due to poor wetting of the skincoat with resin or use of poor quality
resin that causes lack of adhesion of the skincoat to the matting ( I
am paraphrasing from one of the websites suggested by an above poster,
you oughta read it, cuz its got good material). Most gelcoat repairs
fail, even those done by professionals. Since blisters are rarely
structural, the best course may be to simply live with them but
ascertain how your hull is built.

So, here is another idea for blisters: Useless idea #3729

Since blisters are caused by poor wetting of the skincoat, why not
make tiny holes in a large blister and inject very thin epoxy into the
blisters (after forcing as much water out as you can) and then apply
pressure to cause it to re-conform to the hull as much as possible
forcing epoxy out the many holes. There are also materials (think
superglue) that polymerise in the presence of water, maybe inject
them.

Since the professional "repairs" ussually fail, I feel justified in
suggesting ideas.

Parallax wrote:

So, here is another idea for blisters: Useless idea #3729

AHAH! CAUGHT you re-using a number! This should be 3730 or so ;-)

Since blisters are caused by poor wetting of the skincoat, why not
make tiny holes in a large blister and inject very thin epoxy into the
blisters (after forcing as much water out as you can) and then apply
pressure to cause it to re-conform to the hull as much as possible
forcing epoxy out the many holes. There are also materials (think
superglue) that polymerise in the presence of water, maybe inject
them.

Might be an idea, but I just found out that improperly wetted out glass
in our new anchor well did NOT wet out when I put additional on top. I
suspect what little resin was there prevented new resin being absorbed.
In my case, it's of no significance since we put a couple of more layers
of properly wetted out glass cloth over for strength and it's not going
to be a normally-wet area, so blisters will not be a factor.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

Well, because it's easier to just grind out the blister and relaminate. Much
more effective that trying to get that stuff out on a blister by blister
basis.

"Parallax" wrote in message snip

So, here is another idea for blisters: Useless idea #3729

Since blisters are caused by poor wetting of the skincoat, why not
make tiny holes in a large blister and inject very thin epoxy into the
blisters (after forcing as much water out as you can) and then apply
pressure to cause it to re-conform to the hull as much as possible
forcing epoxy out the many holes. There are also materials (think
superglue) that polymerise in the presence of water, maybe inject
them.

Since the professional "repairs" ussually fail, I feel justified in
suggesting ideas.

x-no-archive:yes
Jere Lull wrote:

Parallax wrote:

So, here is another idea for blisters: Useless idea #3729

AHAH! CAUGHT you re-using a number! This should be 3730 or so ;-)

Since blisters are caused by poor wetting of the skincoat, why not

When we hauled our boat for the pre-purchase survey, the surveyor
found blisters, which he showed to me. I saw them. We've never seen
those blisters since on any subsequent haulout. They've disappeared.
This was a (at the time) 19 year old boat.

So I'm not sure all blisters are caused by poor wetting of the
skincoat. Bob thinks that the ones we saw were in the paint.

make tiny holes in a large blister and inject very thin epoxy into the
blisters (after forcing as much water out as you can) and then apply
pressure to cause it to re-conform to the hull as much as possible
forcing epoxy out the many holes. There are also materials (think
superglue) that polymerise in the presence of water, maybe inject
them.

Might be an idea, but I just found out that improperly wetted out glass
in our new anchor well did NOT wet out when I put additional on top. I
suspect what little resin was there prevented new resin being absorbed.
In my case, it's of no significance since we put a couple of more layers
of properly wetted out glass cloth over for strength and it's not going
to be a normally-wet area, so blisters will not be a factor.

grandma Rosalie

S/V RosalieAnn, Leonardtown, MD
CSY 44 WO #156
http://home.mindspring.com/~gmbeasley/id2.html

Rosalie B. wrote:

When we hauled our boat for the pre-purchase survey, the surveyor
found blisters, which he showed to me. I saw them. We've never seen
those blisters since on any subsequent haulout. They've disappeared.
This was a (at the time) 19 year old boat.

So I'm not sure all blisters are caused by poor wetting of the
skincoat. Bob thinks that the ones we saw were in the paint.

My perception is that any "blisters" that don't penetrate through the
basic layup are inconsequential.

On the Tanzer list, we've had a number of complaints of "blisters" at
the waterline, all less than a dime's size; almost all less than a
quarter inch. As I read the descriptions, they were simply gel coat
expanding and contracting differently than the substrate. That sort of
thing is no problem; I know of no cases that got worse than that.

Blisters extend into the hull's structure. The "blisters" that only
affect the surface are of little consequence.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/