Go Back  Bike Forums > Bike Forums > Classic & Vintage
Reload this Page >

Fire as paint remover?

Notices
Classic & Vintage This forum is to discuss the many aspects of classic and vintage bicycles, including musclebikes, lightweights, middleweights, hi-wheelers, bone-shakers, safety bikes and much more.

Fire as paint remover?

Old 01-09-21, 06:53 PM
  #1  
Jicafold
Senior Member
Thread Starter
 
Join Date: Jun 2013
Posts: 1,084
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 360 Post(s)
Liked 128 Times in 88 Posts
Fire as paint remover?

So I had this frame that someone had repainted. Poorly. I started to strip it with paint stripper. I used both Kwik-Strip in the blue can and Jasco in the red can with so-so results. It was taking forever and using a lot of product. So I said "Screw this" and made a fire in the fire pit and threw it in. I then went section by section and the paint came off like butter with steel wool. I was done in an hour. So...my question is...why don't I strip every frame like this? It was so easy and essentially free. See before and after photos. First photo is with paint stripper frustration. Second photo is after melting the paint off in the fire.



Jicafold is offline  
Old 01-09-21, 07:00 PM
  #2  
krakhaus 
Full Member
 
krakhaus's Avatar
 
Join Date: Sep 2012
Location: Palm Springs, California
Posts: 465
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 206 Post(s)
Liked 460 Times in 176 Posts
Works great on carbon fiber bikes.
krakhaus is offline  
Old 01-09-21, 07:04 PM
  #3  
2manybikes
Senior Member
 
Join Date: Jun 2003
Posts: 18,138

Bikes: 2 many

Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 1266 Post(s)
Liked 323 Times in 169 Posts
Some metals change hardness through heat treating If you can remember the sticker or know the alloy you can look it up.
2manybikes is offline  
Likes For 2manybikes:
Old 01-09-21, 07:12 PM
  #4  
Jicafold
Senior Member
Thread Starter
 
Join Date: Jun 2013
Posts: 1,084
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 360 Post(s)
Liked 128 Times in 88 Posts
This was a Bertoni frame made with Columbus SL. That being said, the heat from a camp fire would certainly be less that the heat needed for brazing this frame together. So I doubt it would affect the strength of the steel.

Additionally, and as another comment., I can't bring myself to repaint this "electic rose" or "violet mist".


Last edited by Jicafold; 01-09-21 at 07:18 PM.
Jicafold is offline  
Old 01-09-21, 07:56 PM
  #5  
SurferRosa
señor miembro
 
SurferRosa's Avatar
 
Join Date: Dec 2018
Location: Pac NW
Posts: 8,484

Bikes: '70s - '80s Campagnolo

Mentioned: 92 Post(s)
Tagged: 0 Thread(s)
Quoted: 3846 Post(s)
Liked 6,437 Times in 3,183 Posts
Beavis approved!
SurferRosa is offline  
Likes For SurferRosa:
Old 01-09-21, 08:03 PM
  #6  
thook
(rhymes with spook)
 
thook's Avatar
 
Join Date: Aug 2009
Location: Winslow, AR
Posts: 2,795

Bikes: '83 univega gran turismo x2, '85 schwinn super le tour,'89 miyata triple cross, '91 GT tequesta, '90 yokota grizzly peak, '94 GT backwoods, '95'ish scott tampico, '98 bonty privateer, '93 mongoose crossway 625, '98 parkpre ariel, 2k'ish giant fcr3

Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 919 Post(s)
Liked 745 Times in 546 Posts
Originally Posted by krakhaus
Works great on carbon fiber bikes.
hahahahaha! nice!
thook is offline  
Old 01-09-21, 08:17 PM
  #7  
wesley77803
Member
 
Join Date: Oct 2016
Location: Texas
Posts: 29

Bikes: 1989 Trek 660, 1985 Trek 620

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Liked 12 Times in 5 Posts
Originally Posted by Jicafold
This was a Bertoni frame made with Columbus SL. That being said, the heat from a camp fire would certainly be less that the heat needed for brazing this frame together. So I doubt it would affect the strength of the steel.
The heat from a campfire is definitely enough to reduce the strength of a frame. Also consider that there is a significant loss of strength in the brazing process (look at the Trek brochures from the 80s where they have a chart with strength before brazing and strength after brazing).

The frames are double butted so the material is thicker where the braze occurs. Heating the center section of the tubing would be a bad idea.

For a data point from another field, the US department of transportation requires any steel gas cylinder to be removed from service and condemned if the cylinder is heated to a temperature above 650F, which is much less than a frame brazing temperatures. The temperature limit for aluminum cylinders is lower (350F).
wesley77803 is offline  
Old 01-09-21, 08:28 PM
  #8  
qcpmsame 
Semper Fi
 
Join Date: Jan 2008
Posts: 12,942
Mentioned: 89 Post(s)
Tagged: 0 Thread(s)
Quoted: 1172 Post(s)
Liked 358 Times in 241 Posts
The heat of even a camp fire could change the crystalline structure and bonds of the metals, maybe not drastically, but it has been altered and its strength is compromised to a degree. As a site engineer, for a GC, on DOD buildings, and structures' projects (now retired,) I had to observe and document the entire process if a structural steel pieced had to be field modified, very strict guidelines were laid out, and had to be approved by a structural engineer before proceeding (if you were even allowed to approach the NAVFAC or USACE officers about it.) Mainly it will depend on the particular alloy of the tubes, luge (if applicable,) and brazing materials.

I was teamed with a Supt, that was a metallurgist, in the nuclear power industry, he could really explain this better than I could, and I had to be certified for metals inspections and failure analysis, for my approval as QCPM before each project began, if structural steel and connections were involved. the Supt had been NRC approved for over 20 years, before coming to work for us. Heat treating and failure analysis were kind of his field of expertise and big thing.

There are some very experienced metallurgist and engineers here, maybe one will give their thoughts. Hope that the build turns out well, and that everything is copacetic.

Bill
__________________
Semper Fi, USMC, 1975-1977

I Can Do All Things Through Him, Who Gives Me Strength. Philippians 4:13



Last edited by qcpmsame; 01-09-21 at 08:37 PM.
qcpmsame is offline  
Likes For qcpmsame:
Old 01-09-21, 08:38 PM
  #9  
thook
(rhymes with spook)
 
thook's Avatar
 
Join Date: Aug 2009
Location: Winslow, AR
Posts: 2,795

Bikes: '83 univega gran turismo x2, '85 schwinn super le tour,'89 miyata triple cross, '91 GT tequesta, '90 yokota grizzly peak, '94 GT backwoods, '95'ish scott tampico, '98 bonty privateer, '93 mongoose crossway 625, '98 parkpre ariel, 2k'ish giant fcr3

Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 919 Post(s)
Liked 745 Times in 546 Posts
Originally Posted by wesley77803
The heat from a campfire is definitely enough to reduce the strength of a frame. .
that would really depend on the intensity of the fire and the frame's proximity to the hottest sections of the fire. if i can cook on a campfire without burning the food, it's safe to assume that fire couldn't be more than 400 degrees. and, 400 degrees is really a hot fire to be cooking on, in any case. would sub 400 really be hot enough to alter the metal? hasn't affected any of my cookware in any notable way
thook is offline  
Old 01-09-21, 08:49 PM
  #10  
qcpmsame 
Semper Fi
 
Join Date: Jan 2008
Posts: 12,942
Mentioned: 89 Post(s)
Tagged: 0 Thread(s)
Quoted: 1172 Post(s)
Liked 358 Times in 241 Posts
Originally Posted by thook
that would really depend on the intensity of the fire and the frame's proximity to the hottest sections of the fire. if i can cook on a campfire without burning the food, it's safe to assume that fire couldn't be more than 400 degrees. and, 400 degrees is really a hot fire to be cooking on, in any case. would sub 400 really be hot enough to alter the metal? hasn't affected any of my cookware in any notable way
Measured camp cooking fires and charcoal grilles with pyro-thermostats, at +500* F. One hour is a pretty good length of time, also.

Bill
__________________
Semper Fi, USMC, 1975-1977

I Can Do All Things Through Him, Who Gives Me Strength. Philippians 4:13


qcpmsame is offline  
Old 01-09-21, 09:16 PM
  #11  
thook
(rhymes with spook)
 
thook's Avatar
 
Join Date: Aug 2009
Location: Winslow, AR
Posts: 2,795

Bikes: '83 univega gran turismo x2, '85 schwinn super le tour,'89 miyata triple cross, '91 GT tequesta, '90 yokota grizzly peak, '94 GT backwoods, '95'ish scott tampico, '98 bonty privateer, '93 mongoose crossway 625, '98 parkpre ariel, 2k'ish giant fcr3

Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 919 Post(s)
Liked 745 Times in 546 Posts
Originally Posted by qcpmsame
Measured camp cooking fires and charcoal grilles with pyro-thermostats, at +500* F.

Bill
fair enough. it's like i said, though, it really depends on the intensity of and proximity to. maybe good fortune is the OP's side
thook is offline  
Old 01-09-21, 11:12 PM
  #12  
Jeff Wills
Insane Bicycle Mechanic
 
Jeff Wills's Avatar
 
Join Date: Mar 2008
Location: other Vancouver
Posts: 9,811
Mentioned: 34 Post(s)
Tagged: 0 Thread(s)
Quoted: 788 Post(s)
Liked 688 Times in 367 Posts
Originally Posted by Jicafold
So I had this frame that someone had repainted. Poorly. I started to strip it with paint stripper. I used both Kwik-Strip in the blue can and Jasco in the red can with so-so results.
I've gone to auto parts stores and had them hot tank steel frames to strip the paint. This is caustic soda in hot water- probably not as hot as your camp fire. It gets the vast majority of paint off the frame, only leaving detail work in the corners of lugs and such. It beats messing around with paint stripper goop.
__________________
Jeff Wills

Comcast nuked my web page. It will return soon..
Jeff Wills is offline  
Old 01-09-21, 11:39 PM
  #13  
obrentharris 
Senior Member
 
obrentharris's Avatar
 
Join Date: May 2012
Location: Point Reyes Station, California
Posts: 4,715

Bikes: Indeed!

Mentioned: 92 Post(s)
Tagged: 0 Thread(s)
Quoted: 1504 Post(s)
Liked 3,440 Times in 1,127 Posts
Anyone who has thrown a tin can into a campfire knows that a wood fire can get hot enough to seriously deform thin steel. I remember from my wood stove days that wood starts to combusts at about 500f and that the target for a clean fire without visible smoke is around 1,100f. Some air control was generally needed to reach that temperature so I doubt that an open wood fire would get quite that hot very easily.

Brent

Last edited by obrentharris; 01-09-21 at 11:40 PM. Reason: spelling
obrentharris is offline  
Old 01-09-21, 11:46 PM
  #14  
downtube42
Senior Member
 
downtube42's Avatar
 
Join Date: Oct 2008
Location: Portland, OR
Posts: 3,802

Bikes: Trek Domane SL6 Gen 3, Soma Fog Cutter, Focus Mares AL, Detroit Bikes Sparrow FG, Volae Team, Nimbus MUni

Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 878 Post(s)
Liked 2,019 Times in 1,055 Posts
Brings back memories of working in a heat treating facility in my youth. My part of the shop ran carb pots, and everything was 1500 to 1950 degrees F. One day as i walked through another part of the shop, a guy asked me to help him pick up a heavy shaft he had been straightening. I saw it was not glowing red or white, which to my world meant it was cool. So without thinking I picked it up bare handed. It was 500 F. That was the worse burn I ever suffered.

A roundabout way of saying, 500F is used to soften steel.
downtube42 is offline  
Likes For downtube42:
Old 01-10-21, 04:43 AM
  #15  
alo
Senior Member
 
Join Date: Feb 2020
Posts: 1,060
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 529 Post(s)
Likes: 0
Liked 255 Times in 185 Posts
I would not use heat on a frame. It depends on the frame. In some cases it may significantly weaken it.
alo is offline  
Old 01-10-21, 06:03 AM
  #16  
Wileyone 
Senior Member
 
Wileyone's Avatar
 
Join Date: Oct 2014
Location: GWN
Posts: 2,541
Mentioned: 27 Post(s)
Tagged: 0 Thread(s)
Quoted: 1858 Post(s)
Liked 605 Times in 402 Posts
This is silly.
Wileyone is offline  
Likes For Wileyone:
Old 01-10-21, 06:46 AM
  #17  
oneclick 
Senior Member
 
Join Date: Feb 2020
Posts: 2,887
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 1103 Post(s)
Likes: 0
Liked 1,308 Times in 773 Posts
Originally Posted by Jeff Wills
I've gone to auto parts stores and had them hot tank steel frames to strip the paint. This is caustic soda in hot water- probably not as hot as your camp fire. It gets the vast majority of paint off the frame, only leaving detail work in the corners of lugs and such. It beats messing around with paint stripper goop.
Um, hot water is, by definition (at normal pressure) less than 100 degrees. Wood fires are 600 degrees and up.

Yes it's cooler (but a wood fire is not six times hotter - do I need to say that?).

And annealing temperatures for steel are from about 300 up, so no, fire is not a Good Thing for bike frames.

Last edited by oneclick; 01-11-21 at 05:48 AM.
oneclick is offline  
Likes For oneclick:
Old 01-10-21, 07:16 AM
  #18  
thook
(rhymes with spook)
 
thook's Avatar
 
Join Date: Aug 2009
Location: Winslow, AR
Posts: 2,795

Bikes: '83 univega gran turismo x2, '85 schwinn super le tour,'89 miyata triple cross, '91 GT tequesta, '90 yokota grizzly peak, '94 GT backwoods, '95'ish scott tampico, '98 bonty privateer, '93 mongoose crossway 625, '98 parkpre ariel, 2k'ish giant fcr3

Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 919 Post(s)
Liked 745 Times in 546 Posts
dude....sounds like your frame is... toast...hahaha

but, frankly.....i think your frame just needs s'more paint.....hohohoho

it'll be one smokin' build....<<<buh doomp....pshhh>>>

yes, well done

Last edited by thook; 01-10-21 at 07:24 AM.
thook is offline  
Old 01-10-21, 07:23 AM
  #19  
SJX426 
Senior Member
 
SJX426's Avatar
 
Join Date: May 2008
Location: Fredericksburg, Va
Posts: 9,580

Bikes: '65 Frejus TDF, '73 Bottecchia Giro d'Italia, '83 Colnago Superissimo, '84 Trek 610, '84 Trek 760, '88 Pinarello Veneto, '88 De Rosa Pro, '89 Pinarello Montello, '94 Burley Duet, 97 Specialized RockHopper, 2010 Langster, Tern Link D8

Mentioned: 73 Post(s)
Tagged: 0 Thread(s)
Quoted: 1601 Post(s)
Liked 2,187 Times in 1,092 Posts
I would not even use a torch to burn paint off!

I think your frame is roasted or a t least toast!
__________________
Bikes don't stand alone. They are two tired.
SJX426 is offline  
Likes For SJX426:
Old 01-10-21, 07:25 AM
  #20  
nlerner
Senior Member
 
Join Date: Dec 2005
Posts: 17,127
Mentioned: 480 Post(s)
Tagged: 0 Thread(s)
Quoted: 3788 Post(s)
Liked 6,572 Times in 2,580 Posts
nlerner is offline  
Old 01-10-21, 07:39 AM
  #21  
Kabuki12
Senior Member
 
Join Date: Jan 2016
Posts: 3,404
Mentioned: 33 Post(s)
Tagged: 0 Thread(s)
Quoted: 863 Post(s)
Liked 2,225 Times in 1,248 Posts
Quick and easy is rarely the best solution.
Kabuki12 is offline  
Likes For Kabuki12:
Old 01-10-21, 07:42 AM
  #22  
cb400bill
Forum Moderator
 
cb400bill's Avatar
 
Join Date: Jul 2007
Location: Kalamazoo MI
Posts: 21,321

Bikes: Fuji SL2.1 Carbon Di2 Cannondale Synapse Alloy 4 Trek Checkpoint ALR-5 Viscount Aerospace Pro Colnago Classic Rabobank Schwinn Waterford PMount Raleigh C50 Cromoly Hybrid Legnano Tipo Roma Pista

Mentioned: 58 Post(s)
Tagged: 0 Thread(s)
Quoted: 3059 Post(s)
Liked 6,376 Times in 3,689 Posts
Originally Posted by Jicafold
...I can't bring myself to repaint this "electic rose" or "violet mist".
Why not? It's a great color.
__________________












cb400bill is offline  
Old 01-10-21, 08:31 AM
  #23  
Jicafold
Senior Member
Thread Starter
 
Join Date: Jun 2013
Posts: 1,084
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 360 Post(s)
Liked 128 Times in 88 Posts
Originally Posted by qcpmsame
Measured camp cooking fires and charcoal grilles with pyro-thermostats, at +500* F. One hour is a pretty good length of time, also.

Bill
Let me clarify. The frame was above the fire, not in the coals. I heated one section at a time for about 1 minute, then removed it to scrape the paint in that section. Each section worked was roughly 6 inches long. The total process, section by section, took about an hour.
Jicafold is offline  
Likes For Jicafold:
Old 01-10-21, 09:31 AM
  #24  
Kilroy1988 
Senior Member
 
Kilroy1988's Avatar
 
Join Date: Aug 2016
Location: Visalia, CA
Posts: 2,275
Mentioned: 45 Post(s)
Tagged: 0 Thread(s)
Quoted: 981 Post(s)
Liked 1,838 Times in 608 Posts
See, all of this tripping out about weakening the frame after leaving it in a fire for an hour could have been avoided if you just explained the process earlier. ;P
Kilroy1988 is offline  
Likes For Kilroy1988:
Old 01-10-21, 09:50 AM
  #25  
Jicafold
Senior Member
Thread Starter
 
Join Date: Jun 2013
Posts: 1,084
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 360 Post(s)
Liked 128 Times in 88 Posts
Originally Posted by Kilroy1988
See, all of this tripping out about weakening the frame after leaving it in a fire for an hour could have been avoided if you just explained the process earlier. ;P
True. My apologies. I understand about heat and weakening metal...however, I wouldn't think that it should affect the frame to any dangerous level. I'm not sure if I would do it again or not. It's just that this particular frame had multiple layers of paint and it was taking forever with paint stripper.

Last edited by Jicafold; 01-10-21 at 10:31 AM.
Jicafold is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.