Speedy Auto > Car Tech > 4x4 > Body Chassis

15 Paint & Body Mistakes To Avoid

Use these tips to steer clear of paint issues.

We know that painting your own car is an expensive and scary undertaking, especially if it's your first time using a spray gun. Even though most of us consider ourselves Michelangelo when using a rattle can, a professional spray gun can quickly turn you into a bumbling fool. While we are not trying to scare you out of trying something, we just want to make it known that spraying at home is not as easy as simply pulling a trigger. We have done numerous stories on how to block, prime, and paint, but there are still curable issues we are seeing at shows.

We used our contacts in the industry to get some tips to alleviate the most common things we are seeing. We looked to Craig Hopkins of C. Hopkins Rod & Custom and builder of the AMD Chevelle, "Slick" Vic Sapien from Seaside Collision, Dave Findley of Finish Master, and the good folks at DuPont for information. Some of the tips here will sound like common sense, but our experts all agreed it's the simple stuff that gets overlooked the most, especially when you are doing a job as in-depth as body and paint.

PhotosView Slideshow

<STRONG>1</STRONG> The first and probably most important tip we can pass on is make sure all your products are compatible, from the sealer to the clear. While seasoned painters can comingle brands to save money, that ability comes from years of experience and trial and error. To make it easy on the first-time painter, buy a complete paint system from one supplier. It may be a bit more expensive, but it’s a lot cheaper than having to buy everything again if the paint has an ill reaction.

<STRONG>2</STRONG> Most paints come with a data sheet that will tell you specific mix ratios, dry times, pot life, and coat intervals. With this sheet and a hygrometer, you will know exactly how to mix the material for your air temp, so the paint will act like the manufacturer designed it to. As a rule of thumb, you want to spray when the air temp is around 74 degrees Fahrenheit with about 50 percent humidity. We would not recommend painting in temps below 52 degrees or above 80 if possible.

<STRONG>3</STRONG> So what is a hygrometer? Well, it's a fancy way to say it's a combination thermometer and humidity gauge. Again, this is a crucial piece of equipment for mixing paint since the readings on the gauge will dictate mix ratios or the speed of the reducer used. Painting with the improper mix ratio to temperature can result in blotches, discoloration, dryness, or excessive runs.

PhotosView Slideshow <STRONG>4</STRONG> Remove as much as you can, but carefully mask off items that are not being removed—not like in these photos.

Also, before you lay down your first coat of any material, closely inspect all your masked areas. You want to look for small gaps, tears in the tape, or tape where it shouldn’t be.

<STRONG>5</STRONG> Use the correct product for the job: direct to metal (DTM) sealer for bare steel, primer surfacer over bodywork, and primer sealer over old paint. Primer surfacer has better filling qualities and should be used when trying to build film thickness for blocking.

PhotosView Slideshow A primer/sealer acts more like a barrier between the metal and the paint and is not intended to straighten the body.

<STRONG>6</STRONG> Know what sandpaper grit to use and when: 80 on a D/A to strip something down to bare metal, 40 then 80 then 150 on body filler, 220 then 320 then 400 on the guide coat blocking. If your basecoat is going to be silver, then finish with 500. Also, you need to use sandpaper specially designed for car paint repairs, not for woodworking.

<STRONG>7</STRONG> When using a D/A, keep it flat on the surface. If you tip it on its edge, it will sand a gouge in the paint that you will need to feather out. This just adds more work and if overlooked will leave an uneven finish on the paint.

PhotosView Slideshow

<STRONG>8</STRONG> One common thing we see a lot of is old scratches photographing through the new paint. This comes from not feather-edging the scratches like rings on a tree stump. You want to clearly see all the layers of paint and primer in a nice thick line as opposed to a small strip. Here is a prime example. The sanded area on the left of the circle is not enough; it should look more like the area on the right.

<STRONG>9</STRONG> The black EPD coating should be completely removed from the surface to be painted and coated with a DTM sealer. The EPD coating will protect the inner structure, but you should remove it where you can and reseal it with DTM.

<STRONG>10</STRONG> Get some sort of water trap in your airline. Nothing will screw up a paintjob faster than water entering the gun. If you expect to paint a number of vehicles, then a professional dryer system might be for you. As an added bonus, these dryers will also make all your air tools live longer. If you are just going to spray one vehicle, you can get a disposable inline desiccant dryer like the yellow one shown here for a lot less.

PhotosView Slideshow <STRONG>11</STRONG> Use the correct tip size for the product being sprayed. That means 1.3 for basecoats, 1.5 for clears or sealers, 1.8 for primers, and the 2.0 or bigger will be used for extreme high build or polyester primers.