Seam Sealer: Repair/Clean or Replace?
April 19th, 2010, 01:01 PM
#1
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Thread Starter
Join Date: Jun 2009
Posts: 63
Seam Sealer: Repair/Clean or Replace?
Hey Guys/Gals:
As I am going over the body of the car-cleaning and rust removal, I notice a lot of seam sealer. Took off the back bumper last night and it is everywhere...Duh. I guess it is to be expected. But my ? is: Should you "leave it alone"-just clean and prep for primer, etc...or take out and lay down new??
I think it's one of those if you start removoing, "look out kind of a postion". All thoughts are welcomed. To those in the Memphis, TN Metro area, would love to have you come out and look at my 72 Cali-she was born and raised in California. Thanks...
Steve
As I am going over the body of the car-cleaning and rust removal, I notice a lot of seam sealer. Took off the back bumper last night and it is everywhere...Duh. I guess it is to be expected. But my ? is: Should you "leave it alone"-just clean and prep for primer, etc...or take out and lay down new??
I think it's one of those if you start removoing, "look out kind of a postion". All thoughts are welcomed. To those in the Memphis, TN Metro area, would love to have you come out and look at my 72 Cali-she was born and raised in California. Thanks...Steve
April 19th, 2010, 08:24 PM
#2
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Join Date: May 2008
Location: Austin, Texas
Posts: 3,176
Steve--There are a couple types of seam sealer that the factory used from my experience. I'm not talking about the rope/strip chaulk that is found, for example, up in the side window roofrail weatherstrip channels....I'm talking about the types of seam sealer they would have applied with some sort of chaulk gun.
1) Asphalt/Oil based---this is the black seam sealer typically found on the trunk pan pinchweld (I think this is one you refer to)...you see it clearly when you remove the rear bumper. Same stuff is used at the top of the cowl/firewall seam. This sealer should probably be replaced as it has dried out, is likely cracking, and also isn't firmly adhered to the metal anymore in a lot of spots. This stuff is relatively easy to remove with a narrow scraper, etc.
BUT---you need to REALLY CLEAN the metal under these seams well before spraying anything or applying anything over them as the oil-based nature of the sealer means the underlying metal likely has some oils soaked into it. BAD FOR PAINT ADHESION!!! So---get these areas super clean and then spray them with a good primer (epoxy primer would be best). Then go back with a good urethane based seam sealer and duplicate the "sloppiness" of the factory application if you want to also. There are solvent-based, cheaper seam sealers out there but you might as well seal up these HORIZONTAL SEAMS (IE--water can sit in them!) with a more durable, longer lasting sealer.
You'll ahve plenty of residual spots of the sealer after scraping it. Use something like lacquer thinner or mineral spirits to get the rest off. Lots of rags/paper towels and lots of wiping....the stuff that remains stuck typically doesn't just lift right off of the metal when you apply a thinner or mineral spirits.
2)Solvent based--This is the stuff used on the floor pan and trunk pan plugs. Typically an off white or yellowish color originally. You can get this stuff from 3M in chaulk tubes. Since it's solvent based, it tends to shrink somewhat when it dries. I like to limit the use of this type product to areas where you want the "factory look" like floorpan and trunkpan plugs.
Get the underlying metal clean and then lay down a first layer of protection in the form of a good primer like epoxy primer if possible.
1) Asphalt/Oil based---this is the black seam sealer typically found on the trunk pan pinchweld (I think this is one you refer to)...you see it clearly when you remove the rear bumper. Same stuff is used at the top of the cowl/firewall seam. This sealer should probably be replaced as it has dried out, is likely cracking, and also isn't firmly adhered to the metal anymore in a lot of spots. This stuff is relatively easy to remove with a narrow scraper, etc.
BUT---you need to REALLY CLEAN the metal under these seams well before spraying anything or applying anything over them as the oil-based nature of the sealer means the underlying metal likely has some oils soaked into it. BAD FOR PAINT ADHESION!!! So---get these areas super clean and then spray them with a good primer (epoxy primer would be best). Then go back with a good urethane based seam sealer and duplicate the "sloppiness" of the factory application if you want to also. There are solvent-based, cheaper seam sealers out there but you might as well seal up these HORIZONTAL SEAMS (IE--water can sit in them!) with a more durable, longer lasting sealer.
You'll ahve plenty of residual spots of the sealer after scraping it. Use something like lacquer thinner or mineral spirits to get the rest off. Lots of rags/paper towels and lots of wiping....the stuff that remains stuck typically doesn't just lift right off of the metal when you apply a thinner or mineral spirits.
2)Solvent based--This is the stuff used on the floor pan and trunk pan plugs. Typically an off white or yellowish color originally. You can get this stuff from 3M in chaulk tubes. Since it's solvent based, it tends to shrink somewhat when it dries. I like to limit the use of this type product to areas where you want the "factory look" like floorpan and trunkpan plugs.
Get the underlying metal clean and then lay down a first layer of protection in the form of a good primer like epoxy primer if possible.
Last edited by 70Post; April 19th, 2010 at 08:26 PM.
April 20th, 2010, 05:57 AM
#3
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Join Date: Feb 2008
Location: Plano, TX
Posts: 11,798
70Post summed it all up well!
I have replaced a lot of that black oil based crap, as most was just falling out anyway. Very easy to scrape and wirebrush out.
Then clean well and prime and reseal with a good sealer (I used 3M with good results). Just make sure that interior seams are done with a sealer for interiors. Using exterior sealer inside will leave a long-lasting residual odor.
Also, if the tube says paint in 30 minutes, make sure the sealer has hardened or the paint will bubble up and pull away. Pay attention to thick areas.
given how fast this stuff sets up, reproducing factory sloppiness is easy!
Here is a short demo:
http://www.flickr.com/photos/robsalb...7602930020786/
I have replaced a lot of that black oil based crap, as most was just falling out anyway. Very easy to scrape and wirebrush out.
Then clean well and prime and reseal with a good sealer (I used 3M with good results). Just make sure that interior seams are done with a sealer for interiors. Using exterior sealer inside will leave a long-lasting residual odor.
Also, if the tube says paint in 30 minutes, make sure the sealer has hardened or the paint will bubble up and pull away. Pay attention to thick areas.
given how fast this stuff sets up, reproducing factory sloppiness is easy!
Here is a short demo:
http://www.flickr.com/photos/robsalb...7602930020786/
April 22nd, 2010, 07:57 PM
#4
Registered User
Thread Starter
Join Date: Jun 2009
Posts: 63
Seam Sealer
Steve--There are a couple types of seam sealer that the factory used from my experience. I'm not talking about the rope/strip chaulk that is found, for example, up in the side window roofrail weatherstrip channels....I'm talking about the types of seam sealer they would have applied with some sort of chaulk gun.
1) Asphalt/Oil based---this is the black seam sealer typically found on the trunk pan pinchweld (I think this is one you refer to)...you see it clearly when you remove the rear bumper. Same stuff is used at the top of the cowl/firewall seam. This sealer should probably be replaced as it has dried out, is likely cracking, and also isn't firmly adhered to the metal anymore in a lot of spots. This stuff is relatively easy to remove with a narrow scraper, etc.
BUT---you need to REALLY CLEAN the metal under these seams well before spraying anything or applying anything over them as the oil-based nature of the sealer means the underlying metal likely has some oils soaked into it. BAD FOR PAINT ADHESION!!! So---get these areas super clean and then spray them with a good primer (epoxy primer would be best). Then go back with a good urethane based seam sealer and duplicate the "sloppiness" of the factory application if you want to also. There are solvent-based, cheaper seam sealers out there but you might as well seal up these HORIZONTAL SEAMS (IE--water can sit in them!) with a more durable, longer lasting sealer.
You'll ahve plenty of residual spots of the sealer after scraping it. Use something like lacquer thinner or mineral spirits to get the rest off. Lots of rags/paper towels and lots of wiping....the stuff that remains stuck typically doesn't just lift right off of the metal when you apply a thinner or mineral spirits.
2)Solvent based--This is the stuff used on the floor pan and trunk pan plugs. Typically an off white or yellowish color originally. You can get this stuff from 3M in chaulk tubes. Since it's solvent based, it tends to shrink somewhat when it dries. I like to limit the use of this type product to areas where you want the "factory look" like floorpan and trunkpan plugs.
Get the underlying metal clean and then lay down a first layer of protection in the form of a good primer like epoxy primer if possible.
1) Asphalt/Oil based---this is the black seam sealer typically found on the trunk pan pinchweld (I think this is one you refer to)...you see it clearly when you remove the rear bumper. Same stuff is used at the top of the cowl/firewall seam. This sealer should probably be replaced as it has dried out, is likely cracking, and also isn't firmly adhered to the metal anymore in a lot of spots. This stuff is relatively easy to remove with a narrow scraper, etc.
BUT---you need to REALLY CLEAN the metal under these seams well before spraying anything or applying anything over them as the oil-based nature of the sealer means the underlying metal likely has some oils soaked into it. BAD FOR PAINT ADHESION!!! So---get these areas super clean and then spray them with a good primer (epoxy primer would be best). Then go back with a good urethane based seam sealer and duplicate the "sloppiness" of the factory application if you want to also. There are solvent-based, cheaper seam sealers out there but you might as well seal up these HORIZONTAL SEAMS (IE--water can sit in them!) with a more durable, longer lasting sealer.
You'll ahve plenty of residual spots of the sealer after scraping it. Use something like lacquer thinner or mineral spirits to get the rest off. Lots of rags/paper towels and lots of wiping....the stuff that remains stuck typically doesn't just lift right off of the metal when you apply a thinner or mineral spirits.
2)Solvent based--This is the stuff used on the floor pan and trunk pan plugs. Typically an off white or yellowish color originally. You can get this stuff from 3M in chaulk tubes. Since it's solvent based, it tends to shrink somewhat when it dries. I like to limit the use of this type product to areas where you want the "factory look" like floorpan and trunkpan plugs.
Get the underlying metal clean and then lay down a first layer of protection in the form of a good primer like epoxy primer if possible.
Thanks for the tips! and Rob too! Another question, please: If the seam sealer looks "OK" and has not starting flaking off, should I just clean and prime and move on? or take it all out and do as you instructed? Common sense I guess. Might it be best to put down all new?...oh what a job...
Steve
April 23rd, 2010, 05:53 AM
#5
Registered User
Join Date: Feb 2008
Location: Plano, TX
Posts: 11,798
Try cleaning it and probe it gently in a few places. If it starts to come apart, then I say remove and replace.
If repainting the whole car, I would R&R the black asphalt based stuff - it starts to come apart after 40 years. In hot dry climates, it may be shorter lived...
The white - creamy colored stuff seems to be pretty durable.
BTW, the dried out black stuff is EASY to get out. A small brass wire brush will clean it out in minutes. It is just messy...
If repainting the whole car, I would R&R the black asphalt based stuff - it starts to come apart after 40 years. In hot dry climates, it may be shorter lived...
The white - creamy colored stuff seems to be pretty durable.
BTW, the dried out black stuff is EASY to get out. A small brass wire brush will clean it out in minutes. It is just messy...
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