Stripping paint

Riffing off the Ross Signature paint discussion:

What are the current recommendations regarding stripping paint from a
bike frame? As I recall, Methelene Chloride used to be used in paint
strippers but was banned as dangerous.

My situation is a Cannondale touring bike with old DuPont Imron. That
means it's tough paint over a somewhat softer metal.

--
- Frank Krygowski

On 2/9/2021 10:11 AM, Frank Krygowski wrote:
Riffing off the Ross Signature paint discussion:

What are the current recommendations regarding stripping
paint from a bike frame? As I recall, Methelene Chloride
used to be used in paint strippers but was banned as dangerous.

My situation is a Cannondale touring bike with old DuPont
Imron. That means it's tough paint over a somewhat softer
metal.


Methylene chloride is available from chemical supply houses.
Mix with current 'safe but useless' gel product because the
active ingredient is so thin and volatile it can't stay on
paint long enough alone.

Or bead blast. Or emery. Chemical strip is the most
labor-efficient path.

Always neutralize strippers with a good detergent scrub and
thorough hot water rinse, followed by PrepSol or similar
before you start sanding.

My Friend Pete on the topic:
https://www.youtube.com/watch?v=FAzGvpnvbJY

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

Frank Krygowski wrote:
Riffing off the Ross Signature paint discussion:

What are the current recommendations regarding stripping paint from a
bike frame? As I recall, Methelene Chloride used to be used in paint
strippers but was banned as dangerous.

My situation is a Cannondale touring bike with old DuPont Imron. That
means it's tough paint over a somewhat softer metal.


You might look into getting some NMP. I don't think it'll work
well when cold, and is widely used to strip photoresists at
elevated temperature. The boiling point is over 200 C. PR is
usually stripped at around 80 C.

DMSO (dimethyl sulfoxide) is an even less toxic alternative.
Slightly lower boiling point, near 180 C. Both are much less
toxic than methylene chloride and are miscible with water.
Neither is harmless, but as hazards come and go they're far
from the worst.

Another thought is to use antifreeze. Again, it's not very toxic,
and is well-known to destroy paint. It will be slow, but heat
will help. Best of all, you likely have some already, so it's
a cheap experiment.

Please post what you decide to do and how it works!

bob prohaska

On Tuesday, February 9, 2021 at 10:33:59 AM UTC-8, bob prohaska wrote:
Frank Krygowski wrote:
Riffing off the Ross Signature paint discussion:

What are the current recommendations regarding stripping paint from a
bike frame? As I recall, Methelene Chloride used to be used in paint
strippers but was banned as dangerous.

My situation is a Cannondale touring bike with old DuPont Imron. That
means it's tough paint over a somewhat softer metal.

You might look into getting some NMP. I don't think it'll work
well when cold, and is widely used to strip photoresists at
elevated temperature. The boiling point is over 200 C. PR is
usually stripped at around 80 C.

DMSO (dimethyl sulfoxide) is an even less toxic alternative.
Slightly lower boiling point, near 180 C. Both are much less
toxic than methylene chloride and are miscible with water.
Neither is harmless, but as hazards come and go they're far
from the worst.

Another thought is to use antifreeze. Again, it's not very toxic,
and is well-known to destroy paint. It will be slow, but heat
will help. Best of all, you likely have some already, so it's
a cheap experiment.

Please post what you decide to do and how it works!

The powder coating shop uses bead blasting which also preps the surface for the powder coat which spreads out into an even high gloss finish (well, it COULD be glossier). I have had several bikes finished with this method and not only has it been more than satisfactory but when I was in there several of the local hot rod guys had their entire cars refinished in very bright and glossy finishes.

On 2/9/2021 12:33 PM, bob prohaska wrote:
Frank Krygowski wrote:
Riffing off the Ross Signature paint discussion:

What are the current recommendations regarding stripping paint from a
bike frame? As I recall, Methelene Chloride used to be used in paint
strippers but was banned as dangerous.

My situation is a Cannondale touring bike with old DuPont Imron. That
means it's tough paint over a somewhat softer metal.


You might look into getting some NMP. I don't think it'll work
well when cold, and is widely used to strip photoresists at
elevated temperature. The boiling point is over 200 C. PR is
usually stripped at around 80 C.

DMSO (dimethyl sulfoxide) is an even less toxic alternative.
Slightly lower boiling point, near 180 C. Both are much less
toxic than methylene chloride and are miscible with water.
Neither is harmless, but as hazards come and go they're far
from the worst.

Another thought is to use antifreeze. Again, it's not very toxic,
and is well-known to destroy paint. It will be slow, but heat
will help. Best of all, you likely have some already, so it's
a cheap experiment.

Please post what you decide to do and how it works!

bob prohaska


NMP is N-methylpyrrolidone ?

Products containing that (KleenStrip, Citrus7)are not
capable of stripping paint. Maybe the concentration is too
low? What have you used?

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

AMuzi wrote:
NMP is N-methylpyrrolidone ?

Yes.

Products containing that (KleenStrip, Citrus7)are not
capable of stripping paint. Maybe the concentration is too
low? What have you used?


The key is heat. NMP at room temp does nothing. Even when hot,
100% concentration is not very fast. In semiconductor fabs it
takes minutes to remove a few microns of photoresist at 80 C.
A good paint layer would take an hour, I'd think. And, photoresist,
though it's chemically quite inert, is selected for removability.
Something like Imron, which is specifically selected for non-
removability, is going to be a problem with any chemical one
might want to handle.

I've tried neat (but not anhydrous) NMP on house paint, at room
temp it does nothing. Couldn't heat it in that application.

I suspect antifreeze (ethylene glycol) will be similar, but more
toxic. The advantage is that lots of people already have some on
hand, making it easy to try. If it fails, no great loss.

Bead-blasting, if it's convenient, is probably the quickest.

Thanks for reading,

bob prohaska

On Tuesday, February 9, 2021 at 11:58:23 AM UTC-8, bob prohaska wrote:
AMuzi wrote:
NMP is N-methylpyrrolidone ?

Yes.

Products containing that (KleenStrip, Citrus7)are not
capable of stripping paint. Maybe the concentration is too
low? What have you used?

The key is heat. NMP at room temp does nothing. Even when hot,
100% concentration is not very fast. In semiconductor fabs it
takes minutes to remove a few microns of photoresist at 80 C.
A good paint layer would take an hour, I'd think. And, photoresist,
though it's chemically quite inert, is selected for removability.
Something like Imron, which is specifically selected for non-
removability, is going to be a problem with any chemical one
might want to handle.

I've tried neat (but not anhydrous) NMP on house paint, at room
temp it does nothing. Couldn't heat it in that application.

I suspect antifreeze (ethylene glycol) will be similar, but more
toxic. The advantage is that lots of people already have some on
hand, making it easy to try. If it fails, no great loss.

Bead-blasting, if it's convenient, is probably the quickest.

Thanks for reading,

bob prohaska

The best way to remove paint is with reverse psychology because if you really want paint to stay on, it will fall off. If that fails, I used the Jasco product before it got expensive and weak . . . and (gasp) a heat gun or cool propane torch on my brass brazed frames. Don't try that at home since you could lose a cable guide or other bit. I bet you could get something off the dark web from a meth-lab supply site.

-- Jay Beattie.

On 2/9/2021 1:58 PM, bob prohaska wrote:
AMuzi wrote:
NMP is N-methylpyrrolidone ?

Yes.

Products containing that (KleenStrip, Citrus7)are not
capable of stripping paint. Maybe the concentration is too
low? What have you used?


The key is heat. NMP at room temp does nothing. Even when hot,
100% concentration is not very fast. In semiconductor fabs it
takes minutes to remove a few microns of photoresist at 80 C.
A good paint layer would take an hour, I'd think. And, photoresist,
though it's chemically quite inert, is selected for removability.
Something like Imron, which is specifically selected for non-
removability, is going to be a problem with any chemical one
might want to handle.

I've tried neat (but not anhydrous) NMP on house paint, at room
temp it does nothing. Couldn't heat it in that application.

I suspect antifreeze (ethylene glycol) will be similar, but more
toxic. The advantage is that lots of people already have some on
hand, making it easy to try. If it fails, no great loss.

Bead-blasting, if it's convenient, is probably the quickest.

Thanks for reading,

bob prohaska


Got it, THX.

Methylene chloride doesn't damage the finish itself so much
as blister the primer up from underneath it, which is very
effective:
http://www.yellowjersey.org/photosfr...st/guer15c.jpg

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

On Tuesday, February 9, 2021 at 12:15:08 PM UTC-8, jbeattie wrote:
On Tuesday, February 9, 2021 at 11:58:23 AM UTC-8, bob prohaska wrote:
AMuzi wrote:
NMP is N-methylpyrrolidone ?

Yes.

Products containing that (KleenStrip, Citrus7)are not
capable of stripping paint. Maybe the concentration is too
low? What have you used?

The key is heat. NMP at room temp does nothing. Even when hot,
100% concentration is not very fast. In semiconductor fabs it
takes minutes to remove a few microns of photoresist at 80 C.
A good paint layer would take an hour, I'd think. And, photoresist,
though it's chemically quite inert, is selected for removability.
Something like Imron, which is specifically selected for non-
removability, is going to be a problem with any chemical one
might want to handle.

I've tried neat (but not anhydrous) NMP on house paint, at room
temp it does nothing. Couldn't heat it in that application.

I suspect antifreeze (ethylene glycol) will be similar, but more
toxic. The advantage is that lots of people already have some on
hand, making it easy to try. If it fails, no great loss.

Bead-blasting, if it's convenient, is probably the quickest.

Thanks for reading,

bob prohaska
The best way to remove paint is with reverse psychology because if you really want paint to stay on, it will fall off. If that fails, I used the Jasco product before it got expensive and weak . . . and (gasp) a heat gun or cool propane torch on my brass brazed frames. Don't try that at home since you could lose a cable guide or other bit. I bet you could get something off the dark web from a meth-lab supply site.

PK Jay, that psychological method was really funny. Too bad the lefties have you so convinced that being a slave of the state is such a great thing.

On 2/9/2021 2:15 PM, jbeattie wrote:
On Tuesday, February 9, 2021 at 11:58:23 AM UTC-8, bob prohaska wrote:
AMuzi wrote:
NMP is N-methylpyrrolidone ?

Yes.

Products containing that (KleenStrip, Citrus7)are not
capable of stripping paint. Maybe the concentration is too
low? What have you used?

The key is heat. NMP at room temp does nothing. Even when hot,
100% concentration is not very fast. In semiconductor fabs it
takes minutes to remove a few microns of photoresist at 80 C.
A good paint layer would take an hour, I'd think. And, photoresist,
though it's chemically quite inert, is selected for removability.
Something like Imron, which is specifically selected for non-
removability, is going to be a problem with any chemical one
might want to handle.

I've tried neat (but not anhydrous) NMP on house paint, at room
temp it does nothing. Couldn't heat it in that application.

I suspect antifreeze (ethylene glycol) will be similar, but more
toxic. The advantage is that lots of people already have some on
hand, making it easy to try. If it fails, no great loss.

Bead-blasting, if it's convenient, is probably the quickest.

Thanks for reading,

bob prohaska

The best way to remove paint is with reverse psychology because if you really want paint to stay on, it will fall off. If that fails, I used the Jasco product before it got expensive and weak . . . and (gasp) a heat gun or cool propane torch on my brass brazed frames. Don't try that at home since you could lose a cable guide or other bit. I bet you could get something off the dark web from a meth-lab supply site.

-- Jay Beattie.


Interesting idea. Meth seems to work on teeth from what I
see in the daily mugshots.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971