Black Out Procedure
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Instructor
Joined: Apr 2004
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From: HOMOSASSA FL
Black Out Procedure
Afternoon everyone, I need some information regarding the black out procedure. I have just finished cleaning the road grime off the bottom of the body of my 1970 Corvette. I found some over spray around the driver and passenger seat supports. Is this normal? I thought the last thing they did to the body was the black out procedure... Am I correct? Should there be over spray on the black out? My 1970 has never been painted other than from the factory.Thanks Droop
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...Should there be over spray on the black out?...
Post pics of what you have found.
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Instructor
Joined: Apr 2004
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From: HOMOSASSA FL
The last thing done to the body in the Paint Shop was blackout. After the black out paint was applied and baked, the body then went to the actual assembly line.
There should be no evidence of color coat overspray on the blackout paint unless the car went thru the Paint Repair line. I've heard it said almost every St. Louis C3 went through Paint Repair at least once. That said, the Paint Repair folks generally tried to clean up after themselves.
Post pics of what you have found.
There should be no evidence of color coat overspray on the blackout paint unless the car went thru the Paint Repair line. I've heard it said almost every St. Louis C3 went through Paint Repair at least once. That said, the Paint Repair folks generally tried to clean up after themselves.
Post pics of what you have found.
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Offhand, semi-flat/satin would get my vote, although I'm not quite sure which bracket you mean. Occasionally, some items got a black gloss dip. Quite a lot of the underbody was unpainted.
Last edited by Easy Mike; Aug 13, 2015 at 04:06 PM.
Team Owner
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From: Westminster Maryland
Hi D,
I believe some of the sheet metal reinforcements and other underbody 'plates' were plated and others were painted.
I think typically semi-flat black was used if they were painted, but because many of the parts were 'dipped' they may exhibit a bit more sheen then typical semi-flat black…. but not so much that they might be described as gloss.
So?
Regards,
Alan
An original spare tire bucket bracket.
I believe some of the sheet metal reinforcements and other underbody 'plates' were plated and others were painted.
I think typically semi-flat black was used if they were painted, but because many of the parts were 'dipped' they may exhibit a bit more sheen then typical semi-flat black…. but not so much that they might be described as gloss.
So?
Regards,
Alan
An original spare tire bucket bracket.
Thread Starter
Instructor
Joined: Apr 2004
Posts: 221
Likes: 24
From: HOMOSASSA FL
Hi D,
I believe some of the sheet metal reinforcements and other underbody 'plates' were plated and others were painted.
I think typically semi-flat black was used if they were painted, but because many of the parts were 'dipped' they may exhibit a bit more sheen then typical semi-flat black…. but not so much that they might be described as gloss.
So?
Regards,
Alan
An original spare tire bucket bracket.
I believe some of the sheet metal reinforcements and other underbody 'plates' were plated and others were painted.
I think typically semi-flat black was used if they were painted, but because many of the parts were 'dipped' they may exhibit a bit more sheen then typical semi-flat black…. but not so much that they might be described as gloss.
So?
Regards,
Alan
An original spare tire bucket bracket.
Burning Brakes
Joined: Dec 2006
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From: Bethlehem, PA
I think you are actually asking 2 questions. Blackout and painted/plated parts refer to 2 different things. What Alan is telling you is that the metal parts riveted/bolted to the fiberglass underbody have different finishes and were attached to an unpainted bottom. I'd say they should not have factory overspray. If you want the bottom to look nicer or protect it from rust after your cleaning; clean off unwanted overspray around the parts that were painted, mask them off and paint. But, think about it first. Now you would have a few "restored" parts, where do you stop? Another solution would be to clean the overspray and use a rust converter on the metal parts. It's a milky white brush on product that converts the rust to a black finish. I've used Eastwood brand, but also used Rust-Oleum Rust Reformer found in Walmart.
Thread Starter
Instructor
Joined: Apr 2004
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From: HOMOSASSA FL
I think you are actually asking 2 questions. Blackout and painted/plated parts refer to 2 different things. What Alan is telling you is that the metal parts riveted/bolted to the fiberglass underbody have different finishes and were attached to an unpainted bottom. I'd say they should not have factory overspray. If you want the bottom to look nicer or protect it from rust after your cleaning; clean off unwanted overspray around the parts that were painted, mask them off and paint. But, think about it first. Now you would have a few "restored" parts, where do you stop? Another solution would be to clean the overspray and use a rust converter on the metal parts. It's a milky white brush on product that converts the rust to a black finish. I've used Eastwood brand, but also used Rust-Oleum Rust Reformer found in Walmart.
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From: Crossville TN
A general "rule-of-thumb" for paint sheen is: surfaces get semi-flat (or satin) black paint; hardware components get semi-gloss black paint. NOTHING on a C3 gets gloss black paint nor flat black paint.
Thread Starter
Instructor
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From: HOMOSASSA FL
7T1, Thanks for the information...That is a good rule of thumb. I have a few brackets on the bottom of the body that have some light rust on them. I'm going to experiment off line with different with processes before applying any paint. I want to try to keep it original as possible... Droop
Team Owner
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From: Westminster Maryland
Hi D,
My observation has been that a 2 Level of Gloss "rule of thumb" is a bit narrow for the way the many black painted parts on 68-72 cars were originally finished.
The were certainly a couple of parts with GLOSS black on them typically… the brake booster and fan; some parts with SEMI-GLOSS on them typically…radiators, trailing arms, upper and lower control arms; and some parts with LOW GLOSS on them…brake calipers, rear caliper mounting brackets, and some power steering parts.
I believe the black paint sprayed at St.Louis was SEMI_FLAT, but the vast majority of parts painted black arrived from the suppliers in various levels of gloss. The black sprayed during the build was primarily limited to black-out.
How you proceed depends what you want the under-carriage to look like and how accurate you'd like it to appear.
For many/most people one level of gloss is just fine… but not everyone.
Regards,
Alan
Here's an example of various levels of gloss ranging from the trailing arm, to the caliper, to the frame, to the wheel well black-out.
My observation has been that a 2 Level of Gloss "rule of thumb" is a bit narrow for the way the many black painted parts on 68-72 cars were originally finished.
The were certainly a couple of parts with GLOSS black on them typically… the brake booster and fan; some parts with SEMI-GLOSS on them typically…radiators, trailing arms, upper and lower control arms; and some parts with LOW GLOSS on them…brake calipers, rear caliper mounting brackets, and some power steering parts.
I believe the black paint sprayed at St.Louis was SEMI_FLAT, but the vast majority of parts painted black arrived from the suppliers in various levels of gloss. The black sprayed during the build was primarily limited to black-out.
How you proceed depends what you want the under-carriage to look like and how accurate you'd like it to appear.
For many/most people one level of gloss is just fine… but not everyone.
Regards,
Alan
Here's an example of various levels of gloss ranging from the trailing arm, to the caliper, to the frame, to the wheel well black-out.
Last edited by Alan 71; Aug 17, 2015 at 11:52 AM.
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Boy Alan,
again some amazing ultra detailed pics.
It's shame you don't have a '68, I could use some tutorial pics as well.
Hey you '71 guys pool your $ and support Alan in creating a pictorial AIM for 71's.
All the AIMs are so poorly copied.
I'd live for a pictorial guide with the quality of reference pics like Alan supplies week after week.
Great topic, I learned allot this week about underside blackout.
Thanks,
Marshal
again some amazing ultra detailed pics.
It's shame you don't have a '68, I could use some tutorial pics as well.
Hey you '71 guys pool your $ and support Alan in creating a pictorial AIM for 71's.
All the AIMs are so poorly copied.
I'd live for a pictorial guide with the quality of reference pics like Alan supplies week after week.
Great topic, I learned allot this week about underside blackout.
Thanks,
Marshal
Last edited by marshal135; Aug 17, 2015 at 09:19 PM. Reason: Darn Typo's again Argh public school
Team Owner
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From: Crossville TN
I guess NCRS has made a 'science' out of how many different shades/sheens of black there are in a C3. 
But I seriously doubt that the active system cared that much about 'gloss' on undercarriage stuff. And, different paint manufacturers had different standards regarding gloss levels in their paints.
Someone spec'd a paint mfgr. and product code for various parts, so that's what got ordered. If a different vendor offered a better deal on their "similar" paint, the Purchasing guy probably took the deal and got a meal! That's the way it worked. Then, a different paint brand (and a bit different shade and sheen) showed up at the factory needing it. [I don't believe that GM had any 'Undercarriage Paint Gloss Inspectors' on the rolls.]
But, keep those 'perfect' NCRS books rollin' out. At least, they help the economy....
But I seriously doubt that the active system cared that much about 'gloss' on undercarriage stuff. And, different paint manufacturers had different standards regarding gloss levels in their paints.Someone spec'd a paint mfgr. and product code for various parts, so that's what got ordered. If a different vendor offered a better deal on their "similar" paint, the Purchasing guy probably took the deal and got a meal! That's the way it worked. Then, a different paint brand (and a bit different shade and sheen) showed up at the factory needing it. [I don't believe that GM had any 'Undercarriage Paint Gloss Inspectors' on the rolls.]
But, keep those 'perfect' NCRS books rollin' out. At least, they help the economy....
Last edited by 7T1vette; Aug 18, 2015 at 12:16 AM.
Thread Starter
Instructor
Joined: Apr 2004
Posts: 221
Likes: 24
From: HOMOSASSA FL
I guess NCRS has made a 'science' out of how many different shades/sheens of black there are in a C3. But I seriously doubt that the active system cared that much about 'gloss' on undercarriage stuff. And, different paint manufacturers had different standards regarding gloss levels in their paints.
Someone spec'd a paint mfgr. and product code for various parts, so that's what got ordered. If a different vendor offered a better deal on their "similar" paint, the Purchasing guy probably took the deal and got a meal! That's the way it worked. Then, a different paint brand (and a bit different shade and sheen) showed up at the factory needing it. [I don't believe that GM had any 'Undercarriage Paint Gloss Inspectors' on the rolls.]
But, keep those 'perfect' NCRS books rollin' out. At least, they help the economy....
But I seriously doubt that the active system cared that much about 'gloss' on undercarriage stuff. And, different paint manufacturers had different standards regarding gloss levels in their paints.Someone spec'd a paint mfgr. and product code for various parts, so that's what got ordered. If a different vendor offered a better deal on their "similar" paint, the Purchasing guy probably took the deal and got a meal! That's the way it worked. Then, a different paint brand (and a bit different shade and sheen) showed up at the factory needing it. [I don't believe that GM had any 'Undercarriage Paint Gloss Inspectors' on the rolls.]
But, keep those 'perfect' NCRS books rollin' out. At least, they help the economy....
Team Owner
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From: Westminster Maryland
Hi D,
While the "4 Poets" are occasionally playing loudly on the radio in the garage, on 68-72 Corvettes…..'black' isn't just 'black'.
There's really very little "science" involved; just careful observation of original cars and the information and clues they offer.
Regards,
Alan
While the "4 Poets" are occasionally playing loudly on the radio in the garage, on 68-72 Corvettes…..'black' isn't just 'black'.
There's really very little "science" involved; just careful observation of original cars and the information and clues they offer.
Regards,
Alan
