RE: [CR]UK paint terminology

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Content-class: urn:content-classes:message
Subject: RE: [CR]UK paint terminology
Date: Mon, 4 Dec 2006 13:43:48 -0600
In-Reply-To: <003101c717d9$0eff6870$89ca6851@nonefpfvwek4mv>
Thread-Topic: [CR]UK paint terminology
Thread-Index: AccX2PeewRMZ44WxRMGg6NHqZjmI7gAAJIDw
From: "Watts, Gary J (Vancouver, WA USA)" <gary.watts@hp.com>
To: <classicrendezvous@bikelist.org>
cc: twerne@bellsouth.net

Some of the confusion is mixing materials with process names.

Most all material development for finishes is about improving drying times, hardness or appearance. Lacquer (nitrocellulose) was developed for the automotive industry in the 1910-1920's to speed production times and finish appearance. Lacquer has the lowest solids content of any of the finishes and is the least durable finish. It can be wet sanded (also called color sanding) to remove imperfections and buffed to a very nice shine.

Enamel that's being described here is actually called Alykd Enamel. It has better durability than lacquer but dries slower and defects are more difficult to repair.

Chemical modifications were done in the 1960's to create Acrylic Lacquer and Acrylic Enamel. GM used Acrylic lacquer and Ford used Acrylic Enamel through the 1970's. Acrylic Enamel also has a catalyst hardener that can be added to improve gloss and hardness.

Dupont Imron is a polyurethane enamel. Yet another hybrid, it only cures by crosslinking with the catalyst. It was used for industrial finishing in demanding applications. Drag Racers liked it as the nitro fuel didn't melt it like other paints. I worked in a body shop in 1975 that repainted fire trucks and Imron was the paint of choice, partly because the color needed (a high visibility yellow/green) was only available in Imron.

You can buy clears in any of these paints. Many people refer to lacquering as applying a clear coat, one of the misnomers.

Metal Flake is a brand name from the company that developed the method and materials for 1950's-60's hot rods. Aluminum flakes, rather large in size actually, are applied as part of the coating. Most had piles of clear applied over the top to smooth things out before color sanding.

Metallics are the same idea but using much smaller particles that can be applied with conventional spray equipment. Variations of this are very much in use today.

The majority of the "modifiers" are some sort of top coat. Candies, pearls, transparent dyes etc are all applied over a base coat or color then usually clear coated. You can see just about any choice at http://www.houseofkolor.com. They pioneered making most of these materials avaialble to the public over a very long period of time.

Baking of paints are nearly always a way to speed up drying. The process drives off solvents which was the cure method for all early paints. Newer paints cure by crosslinking and heat speeds it up as well. This is all fine with metal frames; newer carbon frames need to stay well under 150 degrees, the common temperature I've seen for cure booths.

The current finish method for automotive is Base coat/Clear coat or 2 stage paint. A thin layer of color is applied, followed in 10-15 minutes with an optical clear. Because clear is always used, any of the HOK finishes can be used here as well. There are dozens of choices.

2 stage paints go the opposite direction that Imron did. Imron is extremely hard but with hardness comes brittleness and lack of elasticity. It won't stay on flexible parts for example. 2 stage paints are much more flexible and have incredible depth in the clears.

Gary Watts
Vancouver, WA