Paints and Primers
Authored by Wes Vann, last revised on April12, 1997
PLEASE NOTE; I'm not a professional painter (although I've paintedseveral cars during my lengthy years). Some of the information is the resultof products that I have personally used. The remainder is from personsthat I feel are qualified to give honest, unbiased data.
Most of the products listed are from PPG. There are only a few companiesthat produce quality automotive paint products. There is Dupont, Sikkens,and also a German manufacturer whose name evades me right now. (for a latterrevision)
Regardless of the manufacturer that you chose, stick with that manufacturer!!!!
It's a requirement that any time that you spray paint, you wear a filteringmask. With certain paint products, it's also recommended that you havesome form of skin protection.
Due to changing environmental regulations, the availability of certainproducts may be limited or even illegal. New products are released to replacethe outlawed ones.
Any input is welcome!
MAJOR POINT #1!! Except as noted, all primeris porous! Bondo is porous! Spot putty is porous!
The reason for playing this up is that any porous material can, andwill, soak up oil and water. It's possible for water to get through theprimer and rust the metal below. One source of oil that isn't always thoughtabout is from your hands. (during wet-sanding I tend to not worry aboutoil from my hands due to them getting dryed out, however, I've ended upwith fish-eyes due to when carrying the object, I rested it against mychest)
MAJOR POINT #2!! Everything shrinks overtime! Bondo shrinks, primer shrinks. The thicker the bondo, the worse theproblem. Even a thick primer (such as K200) will shrink and if the thicknessvaries greatly, you may notice a wave in the paint a month after beingdone. I like to let the K200 set for a week prior to doing the final sanding.
SEVERAL GENERAL TERMS (currently not inany certain order)
"HVLP" This is a new type of spray gun and the lettersstand for "high volume, low pressure". The idea is that moreof the paint goes on the car and not into the spray booths filters. It'sa good idea that seems to be resisted just due to the cost for new equipmentand familiarity with the old style guns. Here in L.A., they are requiredby law in a production shop.
"SINGLE STAGE PAINT" This is where there isn't a clearcoat added over the color coat. It's not as costly, however it doesn'thave as much luster and metallics tend to fade faster. When the paint ismixed, there is more clear added to the mixture.
"BC/CC" This is a two stage paint and the letters standfor "base coat/clear coat". You will get more luster and lessfading. As you could guess, first the color is sprayed, and then top coatedwith a clear.
"HIGH SOLIDS" Solids are the part of the paint thatremains after the chemicals evaporate.
"PEARLS" A pearl is an additive that is added to theclear coat. It gives a reflective quality just like a pearl. The colorof the pearl doesn't have to be the same as the base color. As a resultyou could create things like ghost flames that are only visible when thelight hits it just right. It's real difficult to get good results sprayingpearls due to the fact the amount of clear/pearl that is sprayed controlsthe amount of the reflective quality. It's not something that may be visiblewhile spraying.
"Rustoleum" (I had to put this somewhere) This is agreat paint for rust control on your lawn chairs! Don't use it on yourcar. From what I understand, the reason that this product works so goodis that it has a fish oil base. As a result, you will never get anotherautomotive paint to flow correctly over it.
"ORANGEPEEL" Just like the name would imply, this describesthe surface texture of the paint. Basically, it's due to the paint notflowing prior to taking a set. Painting is a trick due to it being a balancebetween getting runs and ending up with orangepeel.
"FISHEYES" This is where the paint looks like somebodyjabbed at your paint with a pin.The main reason is due to there being oilon the surface painted. It could something as simple as oil from your handswhen you leaned on the car. You should always wipe the car down with awax remover. (PPG DX330) There are additives that can be added to helpprevent fisheyes however, they also increase the probabilities of gettingruns.
"HARDENERS AND CATALYSTS" There are several additivesthat can be added to paint that will cause the paint to set-up faster,have more luster, etc. It's very highly recommended that you stick withone manufacturer's product line!
Back in the good old days (??) seams were filled with lead. This wouldmore accurately refered to as solder due to it being a combination of tinand lead. It requires a coating of tinning flux that if not neutralizedwill seep out of the gaps and ruin a paint job. Lead is toxic and can leadpoisoning! One of the nice things about lead is that it will not shrink.
BONDO AND PUTTYS;
Bondo; This started as the manufactures name and has become ageneric term. It requires that you mix it with a cream hardener. The hardeneris colored so that you can judge how much hardener was added.
If you add too much hardener, you may not be able to apply it beforeit kicks. Another problem is that it will be more brittle.
If you add too little hardener, it may never kick.
If you have never played with this stuff before, do several test mixesand keep track of the color.
I tend to use "dynalite" brand and it should be noted thatit is not waterproof! If this may cause a problem, I'd recommend "Duraglass".
Glazing Putty; Evercoat has a great glazing putty that mixeslike "bondo". What makes this a nice product is that it spreadsmore smoothly than bondo. It sands a little easier.
Spot Putty; Spot putty air drys and should only be used for fillingpin holes or chips in the paint. 3M sells it in three different colorsand they all are supposed to work the same. I've had good luck with thestandard RED and GREEN, however the BLUE just doesn't seem right.
Tigers Hair; This is more of a fiberglas product than a Polyesterfiller. It has chopped fiberglass fibers in the mix. One of the problemsis that (much like the fiberglas that it is) it's fairly brittle. The stuffis great if building a custom part, but shouldn't be used for normal bodyrepair.
RUST CONVERTERS, POR15;
I have to admit that in the past I considered this type of product inthe same light as snake oil. I haven't used POR15 it's self, but have useda product called "Marhide" that I believe to be the same thing.
This stuff is great and really does convert surface rust into an inertpaintable material. By saying inert, it means that the converted materialcan't rust. It would however be possible to chip off the materialand allow rusting of the material below.
In order for the stuff to work, it has to be able to get to the rustedarea. You should use a wire wheel on a drill motor or wire brush to removeall of the loose flaking rusted metal prior to brushing on the chemical.As it works, it turns black. (as an added note, it will also turn yourhands black!)
PRIMERS, AND SEALERS;
You should never spray your paint directly on the bare metal. A primerwill help adhesion of the paint to the metal surface.
Should you be painting over an existing painted surface, a "sealer"should be used to ensure that there is no bleed of the old paint into thenew paint. As an added note, you should never try to paint lacquer overan enamel (if the enamel was noncatalyzed).
There are several "DP" primers manufactured by PPG. The onlydifference is in the color with DP90 being black. They all require thatyou mix them with DP402 hardener.
This is a high fill primer that has to be mixed with K201 and is manufacturedby PPG. This stuff is a light mustard color, goes on thick, and is blissto sand. Although hard enough to sand after about 2 hours, it;s best tolet it set overnight in order to have it finish shrinking.
Lacquers; Lacquers are a thing of the past here in L.A. due tothe environmental problems. It is a very brittle paint that chips easy.I've used it in the past and one nice thing is that it drys very quickly.Any runs or problems can be sanded out and resprayed in an hour. It doesrequire that the finished product be rubbed out and polished! When youread about somebody rubbing out a lacquer, it's not just for the fun ofit!
DXR80; This isn't a paint, but is an additive that is added toenamels as a "Urethane Hardener". It's added to enamel basedcolored paints and also clears. An enamel mixed with this hardener willhave to be sprayed within a few hours.
PPG Delstar; This is the enamel that I normally use. It's anacrylic enamel and I recommend the addition of PPG DXR80. It drys quicklyand can be wet sanded the next day.
DURETHANE; This is a Polyurethane paint (and clear) and requiresa hardener (DU5 or DU6). A polyurethane paint would be more durable thanan enamel and should have a higher gloss. Once mixed, you have severalhours to spray it and clean out your spray gun.
Imron; This was popular years ago. I would have to describe itas a rubber based polyurethane. It was originally designed for airplanesthat are subjected to extreme temperature changes. It then was used onfleet trucks. The stuff does not chip. Brake fluid will not damage it.If you get a run, you can't sand it out! This stuff is so toxic that whenI sprayed it, I breathed off of a scuba tank! You have to clean out yourgun when done, or throw the gun away. The left-over paint will bounce likea ball.
This is the compressor that I use. It's the largest that Sears had thatwouldl run on 110 voltage. (I didn't want to wire the garage for 220) Ithas a flow capacity of 9.0 cubic feet per minute. The only tool that ithas a problem with is the DA sander.
When looking at compressors, you have to be concerned with the amountof air that it can continue to put out. If the flow capacity isn't adaquate,you will have a drop in pressure and you will have to stop until the tankcan refill.
What isn't shown in this photo is that I have a separate regulator andwater separator that plugs into the air line.
On any compressor, it is required that you drain the tank periodicallyin order to remove any moisture caused by condensation. There should alwaysbe a drain petcock at the bottom of the tank.
You should always use some form of sanding block. I'll include photosat a latter date, however, they are fairly standard.
This photo shows an "air file" and also a manual board. Theyrequire a special sandpaper that is longer than the normal paper. Theseare great for getting a large flat area. As far as I know, it's not possibleto get a wet-or-dry paper in this size. It is possible to get very finepaper (and also very course)
This is a DA, or Dual Action sander. They are good for blocking downan area, however, it's possible to sand in a low spot. They require anexcessive amount of air volume and I can't run mine for very long withthe compressor that I have. The truth of the matter is that I really don'tmiss it!
These are the two guns that I use. Both are by DeVelbiss and are professionalquality. It's possible for a good painter to use almost any gunand get around a bad spread pattern. (I need all of the help I can get!)
The small gun is normally called a "touch up" gun. It's realhandy for spraying small items or door jambs.
The orange item on the end of the small gun is a "throw-away"water separator. It's on a quick disconnect and can be transfered to thelarge gun. Condensation can (and will) form in the air line between thecompressor and the gun.