"Old" Urethane vs. Current Urethane

Discussion in 'Finely Finished' started by EsquireOK, Aug 17, 2019.

  1. EsquireOK

    EsquireOK Friend of Leo's

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    Hello,

    I've always thought it would be nice to reproduce Mick Ronson's Tele, which to the best of my determination is probably a circa 1969 or so in Lake Placid Blue. (It has a rosewood veneer board with a truss rod plug.)

    Being that such a guitar's body would have been urethane finished, it theoretically makes a body quite a bit easier and cheaper to track down than a replica built based on a nitro finished year.

    However, I have always noticed that even the older urethane finished Fenders experience wearthrough eventually. For instance, look at this '69 photo that I pinched from a completed Reverb listing:

    olmyl9zbiyfjubs0fx0q.jpg

    That's definitely not something that would happen with a "modern" urethane finished body.

    So how do I recreate these late '60s custom colors so that they naturally wear this way over time? What was different about the old urethane that Fender used? Is that exact material still available today?

    Thank you.
     
    Last edited: Aug 17, 2019
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  2. Matthias

    Matthias Friend of Leo's

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    I’m not sure Fender ever used nitro for metallics - they used acrylic lacquer. When they stopped using nitro, I hazard a guess they kept using the acrylic until the spangly colours were discontinued and they started painting everything in shades of brown!

    The late 60s/70s urethane coatings did rub through though. They just checked and generally wore a bit differently... I imagine it can be done with a thin layer and some standard weathering techniques.
     
  3. EsquireOK

    EsquireOK Friend of Leo's

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    Thanks.

    Just be clear, I do not want to "Relic" the finish. But I do want it the same as original, so that it will wear the same way over the years.

    Fender used acrylic color and nitro clear for most metallics. The exception is Sherwood Green, which was nitro color and nitro clear. (They didn't ever use acrylic clear.) Oly White was also an acrylic color coat – the only non-metallic finish they had that used acrylic color coats.

    They certainly sprayed urethane clear over nitro lacquer all through the '70s (and late '60s). Sunburst color coats were nitro burst colors with urethane clear. It would not surprise me if they also sprayed urethane clear over acrylic for certain colors. But some verification of this would be cool to have.

    I have also seen the same sort of wear on typical '70s blonde and or or white Teles, so yes, the urethanes of those years would wear through eventually. The real question is why the older urethane wore through with gradual abrasion, while modern ones wouldn't ever do so – nowhere close. I wonder what the difference in materials is.

    It has been a nagging question for some time, but I didn't ever dive deeply into it, because the occasion had never arisen for me to reproduce a guitar from the poly years.
     
    Last edited: Aug 17, 2019
  4. schmee

    schmee Poster Extraordinaire

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    The old colored finishes were just car paint/acrylic lacquer were they not? Which is not nitro... But yeah, there's Urethane, polyurethane, 2 part polyurethane (Big Fender mistake) , polyester. Some of today's are polyester i think. My MIM Strat wore through readily, but there is a base coat that is thick and just not going to wear through. So I guess the color coat was not that thick. (Same guitar)
    [​IMG]
    [​IMG]
     
  5. EsquireOK

    EsquireOK Friend of Leo's

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    I am very surprised to see that wear through on a MIM Strat. The finish of both of my MIM Strats is like glass; I can't see ever wearing through it in the slightest (though it does chip, of course). Do you always play in a biker jacket or something?
     
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  6. EsquireOK

    EsquireOK Friend of Leo's

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    P.S. One thing I do know is that the coatings they switched to in '68 were called aliphatic urethane coatings. Whether that is any different that what "poly" or "urethane" is today, I do not know.
     
  7. Silverface

    Silverface Poster Extraordinaire Ad Free Member

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    It certainly can. Having run accelerated wear tests on modern finishes, they wear through as well.

    They did use acrylic clear at times, and also nitro/acrylic blends

    They often had architectural lacquers mixed to match auto colors at the local paint stores, and in some cases they bought auto finishes. And they used several different primer/sealers, which often affected the colors as they age (Dakota Red is a great example - a broker I work with and I lined up 6 Dakota Red guitars - all original - and we had 6 different colors.

    Some car finishes were nitro/acrylic blends as well.

    Tht's because aromatic urethanes are not colorfast and are industrial protective coatings only. The aliphatic versions are used where color is a critical factor.

    And that's about the ONLY thing that is an absolute fact. Fender did not use the same systems consistently - they used whatever was in stock or they could get fast. In a few cases there are original guitars with oil based enamel color coats! In the Leo days if they needed something fast an employee was sent down to Fullerton Paint to pick up a gallon of whatever they had in stock that could be tinted to the required color.

    They were NOT very concerned with what a guitar would look like 15 years later - through the early /mid 60's they were still running on a shoestring and generally made everything "JIT" - Just in time. Fill the backorders in whatever way was fastest.

    The early CBS years were just as inconsistent, but due to purchasing agents sending 1 year supply contracts out to bid, trying to save money...and also buying bulk quantities, sometimes of "wrong" materials. Do you think those were discarded? HA! No, they were used up.

    The thing to remember with Fender finishes - stock and custom - up to the 70's is that the only absolute rule is that there was no absolute rule. Nothing was ALWAYS or NEVER used, and no finish system or color was always done using the same materials.

    Having done all sorts of lab tests on vintage Fenders (and other brands) including chemical testing of finishes, I've found the inconsistencies to be widespread.

    So when you try to duplicate something, you can use almost any coatings system that was available at the time and you'll duplicate the finish on SOME run of guitars!

    This link has some - not all - info about Fender custom finishes. It's not 100% correct, but not much is unless it comes from a combination of sources - mostly stories from Fender employees at the time and those in the industry who have also worked in coatings manufacturing and actually used coatings test equipment on hundreds of examples.

    http://guitarhq.com/fenderc.html
     
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  8. Bluey

    Bluey Tele-Meister

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    Vehicle colours are mixed in batches of a particular code/name. They do have a basic formula of tinters for each code but can still vary from batch to batch. When matching for repairs etc. you mix off the manufacturers formula but 99% of the time you need to add/subtract certain tinters in the formula to get a exact match. Before early 70's auto paint was acrylic which needed to be buffed & polished. Because it was very time/labour consuming plus fades, wears & chalks rather quickly. It was replaced by urathane with hardener additive ( 2K ) which produced a gloss finish strait off the production line, way more durable, way less prone to being sctatched & needing major repair before delivery to the customer.
    2K solid works very well on wood but metalics need the porous colour base coat laid down with a 2K clear coat over the top. However 2K clear flakes, lifts & can be blemished by the timber. So I'm guessing thats why guitars went with nitro after acrylic went by way of the dinosaur.
     
  9. Telekarster

    Telekarster Tele-Meister

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    As I understand it there are virtually no paints, nitro lacquers, etc. that exist today vs. what they used prior to 1970's. The chemical ingredients they used then are not the same, due to the banning of so many of them due to EPA etc. as well as the mfg's creating better lasting finishes for the public as a whole too. So, while we can get close to the finishes of those times, we can't get 100%. The nocaster I recently built to 1951 specs is certainly aging and "buttering" like the originals did. I just think it takes longer for some of these modern paints/finishes to react to wear and tear more than the older finishes due to these nuances. just my 2 cents
     
  10. Silverface

    Silverface Poster Extraordinaire Ad Free Member

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    Respectfully - There's no difference in fading between acrylic and nitro or acrylic/nitro blend lacquers. Fading is caused by specific colorants used and reduced by additives used for UV resistance, which are part of all lacquer formulations. And acrylic resins chalk less than any other than aliphatic polyurethanes and polyesters.

    Acrylic lacquers are also no more time consuming than nitros and blends. Unless made with slow drying solvents like naphtha in the formulation (or a catalyzed material) they dry only by evaporation - there is no cure time - and use the same solvents, which is why they are compatible with each other (i.e . can be applied over each other and will melt into a single coat of blended resin).

    There is no absolute as far as wear resistance between acrylic and nitrocellulose lacquers. Abrasion, impact and scratch resistance are all run through the same routine ASTM test methods and each is balanced/equalized by addition of various additives. some acrylics have better abrasion resistance than some nitros; some nitros have better impact resistance than some acrylics.

    It boils down to the specific formulation. And most of the shift was not from acrylic to nitro, but from conventional types of either to catalyzed(plural component) formulations or polyester (or polyurethane) systems.

    The performance of the products is virtually the same because the changes were in the solvent blends and amounts and the percent of solids by volume (the amount of what is in a can that ends up staying on the surface and not evaporating.

    The reductions are in emission of "volatile organic compounds" (VOC's) during manufacturing, application and drying/curing as applicable. VOC's are primarily contained in specific solvents and some additives. Very little in resins themselves.

    I was on the coatings industry working committee in the 1980's/90/2000's that negotiated changes in regulations with the Los Angeles and San Diego Air Quality Management and Air pollution control Districts and the California Air Resources Board. Surprisingly, lacquers were (generically) one of the product lines that had the least affect on performance. Lacquer was affected in solids content application/drying/during, and most Southern California lacquer production application (large volume - cabinet shops and metal components) moved to northern Mexico.

    Small applicators ended up with less material in the can, lower viscosity and big changes in application methods and limits on the amount that could be applied each month.
     
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  11. Telekarster

    Telekarster Tele-Meister

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  12. Bluey

    Bluey Tele-Meister

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  13. Silverface

    Silverface Poster Extraordinaire Ad Free Member

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    @Bluey said: "I don't know where you googled that from. My comment was between automotive coatings, in which acrylic was used in the early days by Fender, probably & most likely, because colours were mixed & readily available . Everyone in the automotive industry for decades have been well aware that 2K is far more resilient & less time consuming to apply than Acrylic. Nothing was mentioned in the comparison between acrylic & nitro. But I guess that mutes an argument.or does it?"

    If you read my post completely I didn't "Google" the information from anywhere - I worked in the industry for almost 40 years.

    To clarify for those in the US "2k" is not a specific coating, it's a generic description for any plural component, chemically-cured coating such as to component epoxies and acrylic, aliphatic and aromatic urethanes. Only in the last 5 years or so have products been labeled as "2k" products in the US, and "2K' is not a *type* of coating - it ONLY means a chemical activator or hardener is required, i.e. a 2-component product. "2k" may mean something different in Australia.

    And Fender's coating usage was (and is) subject to very restrictive air quality regulations that essentially "randomized" what products were sued for specific colors.

    Fender initially started using some 2-component aliphatic urethanes in the 70's, but it was a slow transition requiring completely different application equipment, techniques, suppliers, VOC emission compliance (under South Coast Air Quality Management District rule 1136, Wood Products Coatings) and adapting to adapting to various product curing cycles instead of the fast evaporative drying of lacquers.

    Fender could ONLY use products that complied with Rule 1136 - not the automotive coating's Rule 1151 (see below). They were NOT urethanes manufactured for the automotive market - they were "architectural" versions (manufactured under Rule 1113, "Architectural Coatings" - have I lost you yet? :lol:) that could be used on some wood products due to VOC regulations that limited *product* emissions "as manufactured" (VOC's per liter of liquid coating) and separate VOC emissions during application.

    Because most "auto repaint shop coatings" available in Southern California were made and sold in compliance with with the most restrictive air quality rule (the South Coast Air Quality Management District's rule 1151, Motor Vehicle and mobile Equipment Non Assembly Line Coating Operations) - requiring "cradle to grave" (manufacturing to application) tracking of VOC's emitted by date they could not be sold for other uses - like guitar manufacturing subject to Rule 1136.

    The MOST RESTRICTIVE rule always applied, meaning many automotive coatings could not be sold for use on wood products. The rules have changed a bit and some automotive coatings can be sold for non-auto applications. But not all of them.

    So in the 1970's Fender often had automotive colors mixed in single-component products, or architectural aliphatic urethanes (acrylic urethanes were not available in the 70's, 80's or 90's. At least legally) - whatever they could get.

    In simple words, just as in the 1950's and 60's Fender used whatever product was quickly available and that no absolute statements can be made about what was used until roughly the early 1990's.

    Whatever was going on in Australia in the 1970's, it didn't apply to Fender's operations, which were subject to 3 different air quality regulations. And at the time, there were no coatings known as "2k" in the U.S.

    I hope that wasn't TOO confusing.
     
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  14. Skydog1010

    Skydog1010 Tele-Holic Ad Free Member

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    The best I can tell is:
    Some colors are applied differently.

    Recent FSR came with alder, no base coat or Fullerplast, super thin silver undercoat, and candy apple Red like micro thin also. The entire finish is less than 1 mil, more like 3-4 microns.

    Very impressive, most likely applied by robot.

    To say these current finishes vary greatly is a huge understatement.
     
  15. Bluey

    Bluey Tele-Meister

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    Never lost me but bored me. I've been in the industry for 43 years & if you read my post? I specifically stated "automotive" coating & the change in the industry from acrylic to urethane ( 2K ) lead by industry leader Dupont which has used the term urethane (2K) since its inception, there is only one, & as noted on PDS. Also Thanks for confirming my assumption/statement of why Fender may have ceased with the Dupont Acrylic automotive colour coatings they were using on guitars about the same time Pontiac & all the rest went from Acrylic to 2K.
     
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