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Hi: I have a question for the painters out there. What are the differences between nitrocelllose and acrylic laquer? Also which type would have been used on a 1963 vette? len #39247
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Re: Nitrocellulose VS acrylic laquers?
nitrocellose laquer was used from the late 20s to late 50s. acrylic was most likely used on your 63. -
Re: Nitrocellulose VS acrylic laquers?
My 70 used acrylic, but Hirsch auto products is a couple of miles from me.Been around forever, supplies lots of restorers with nitrocellulose lacquer. He can match my donnybrook green and its cheaper than acrylic lacquer. Have to speak to Bill Hirsch to get the specifics.
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Heard At Park City...
Ken Schow, the professional Corvette painter that presented the paint seminar at the just finished National Convention, said he saw no advantage to using nitrocellulose laquer on ANY restoration including the old C1s that used it originally. FWIW.
BTW, I think the first year for acrylic lacquer was 56.Comment
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Re: Nitrocellulose VS acrylic laquers?
I don't know the detailed chemical difference, but acrylic lacquer has a longer lasting shine. The old nitrocellulose formulas required frequent buffing to cut down the oxydized surface layer and bring back the shine, which provided me with plenty of of car detailing business around the neighborhood in my youth.
I recall that the Williams family new 1959 Pontiac Bonneville station wagon had a "Magic Mirror" acrylic lacquer finish, and I learned much later that the first acrylic lacquer use on Corvette was IIRC 1957 Inca Silver, and in 1958 all Corvettes were finished with acrylic lacquer. Acrylic lacquer was subsequently used for all Corvettes built at St. Louis.
DukeComment
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Metallic Colors--When?
Does the advent of acrylic correspond to the use of metallics? When were they introduced?Comment
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Re: Nitrocellulose VS acrylic laquers?
Duke,
I recall that GM used to advertise that the Magic Mirror lacquer finishes were "fire-levelled" by some oven process of re-flowing the paint. Given my albeit limited experience with the fast-drying properties of lacquer, I find it difficult to conceive of there being much "levelling" going on, but if GM went to the trouble it must have been of some benefit.
GrantComment
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Re: Metallic Colors--When?
I'm not sure if there were any metallic colors in nitrocellulose or if the first were acrylic.
DukeComment
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Re: Nitrocellulose VS acrylic laquers?
There are two kinds of plastics. One will melt and can be reformed, the other goes through a chemical change as it hardens and cannot be reflowed.
I think the former type are known as "thermoplastic" and acrylic lacquer is a member of this family. As I'm sure you know, acrylic lacquer remains soluble in lacquer thinner even long after it has hardened. Following the final finish coats, steel bodied GM cars were baked briefly at something on the order of 400-500 deg. F, which caused the lacquer to "flow out". They went in dull and came out shiny and required little if any buffing.
Corvette bodies were also baked, but at a lower temperature due to the fiberglass. The lacquer didn't flow out as much as on steel bodied cars, so Corvettes required some buffing to bring out the full shine.
Lacquer was only used on GM cars in that era. Trucks - light duty and up were finished with conventional alkyd enamel and later acrylic enamel.
DukeComment
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Re: Nitrocellulose VS acrylic laquers?
Grant -
DuPont developed the "Magic-Mirror" acrylic lacquer for Fisher Body, which "re-flowed" (self-leveled) to some degree in a 350*F final reflow oven, which reduced the amount of final polishing/buffing required to achieve the required gloss level. This basic DuPont OEM formulation was used for many years in all GM plants until NAD (non-aqueous dispersion) lacquer was developed in the early 70's, later replaced by waterborne and solvent-borne basecoats and clearcoats.
The Corvette body couldn't be baked at "reflow" temperatures due to fiberglass material limitations, so St. Louis-built Corvettes really didn't benefit from the formulation; Corvettes continued to get whatever gloss level they had primarily due to post-bake polishing and buffing until the newer paint technologies were introduced when Bowling Green opened in 1981.Comment
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Magic-Mirror Paint....
Grant,
The "reflow" process used at the St Louis Corvette plant in the 60's and 70's is somewhat misunderstood. When we think of paint reflow, we assume that all of the texture and orange peel is removed in the process but this isn't exactly the case. The process actually did reflow the paint but only a VERY thin top layer, which produced some minor leveling but mostly, it produced gloss, and it worked. If you study the paint on an original paint Corvette from this era, you will see that much of the coating in areas that couldn't be buffed, is quite reflective/shinny, but still retains some roughness. Door jambs are a good example. Some areas look like they have been hand polished but we know full well that this never happened at the plant. The only part of the body that was buffed at the St Louis plant after Final line was mostly the horizontal surfaces and vertically down to the body line on C2. The area below the body line was never touched but it still had an excellent gloss because of the surface reflow.
The paint for the St Louis plant was unique and was NEVER available to the public. It was specifically designed for OE use and made from a completely different formula than the paint mixed for the field, or service. OE paint contained "fluidizers" that were designed to kick, or reflow, at a much lower temperature than normal aftermarket paint. That's why a fiberglass body could go through the reflow oven on the assy line without damage to the body. Paint for the field, or aftermarket, was called a "rubbing/polishing" formula but OE paint was called a "reflow" formula. Completely different stuff.
MichaelComment
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Re: Magic-Mirror Paint....
Duke, John & Michael,
Thanks for the interesting info!
grantComment
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