Blending Paint Correctly - How To
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Refinish

Blending Paint Right the First Time

Because nearly every repair ends up needing blended, you need to get it right the first time or you can kiss your profits goodbye.

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Aahh, the good old days.

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Remember when you’d get a body job – like replacing a hood? You’d order the hood and call the local paint store to order the paint, usually acrylic enamel or acrylic lacquer. After installing the hood, you’d mask off the fenders and paint the hood. Of course, 90 percent of the time, it didn’t match.

The good thing was, it wasn’t expected to match.

If the customer complained, you could always blame the paint company. “It’s the only formula they have,” you’d say.

If you were lucky, you’d have stripes on the fenders so you could at least paint over the top of the fender to hide the mismatch. Yep, those were the days.

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But those days are gone.

Today, one of the biggest assets in refinish technology is the ability to blend. Done properly, blending can actually allow you to take a paint formula that would’ve been unacceptable 15 years ago and create a match to the eye.

And that’s the only reason for blending – to trick the human eye into believing the paint matches.

Almost every repair that goes through your shop will end up being blended in some manner. Luckily, blending isn’t rocket science. It’s simply a way to make your job easier and your customers happier.

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With that said, let’s get started …

1. Plan the blend.

The ideal time to decide which panels will be blended is before the repair has started. This way, the technician can have a game plan as to what panels to prep. Proper preparation is vital to the appearance and durability of the repair.

On a body side repair, the blend is pretty clear cut as to where it will be. Just blend to the center of the adjacent panels. On a horizontal panel, such as a hood or trunk lid, the basecoat should be blended off, over a crown in the adjacent panel. Light is reflected at different angles on a crown, so it’s easier to hide the transition of a less-than-perfect paint match.

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Blending doesn’t always mean refinishing more than one panel. An example would be if you had a fender with damage on its front edge. You could blend the color to the center of the panel, then clear the panel to the back edge. Only one panel gets refinished, but you still used a blending technique.

2. Perform the body repair.

3. Scuff and prep.

After the body repair is complete, scuff any panel that will be blended into with basecoat and cleared according to the paint company’s recommendations. This includes any areas that you’ll be blending the clear into, such as a C-pillar. Many products available today – scuff pads and prep liquids – do an excellent job quickly. You can also wet sand panels with a fine sandpaper, 1,500 grit or finer. Remember that if the panel isn’t scuffed properly, you’ll end up with a delamination problem in the future. Spending an extra 15 minutes on a panel today will save you from an expensive re-do later.

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4. Mask and prime.

All the major paint companies today offer a color-keyed primer system that aids in the hideability of the basecoats. If you choose not to use a color-keyed primer, you should apply a color-keyed ground coat over all the repaired areas, just prior to applying the basecoat. (See Step 7.)


5. Head for the booth.

Once the vehicle is in the booth, mask off any panels to be blended that didn’t get masked from the primer in Step 4. The idea is to limit the amount of basecoat applied to those panels. By masking them off, you can control the amount of paint that’s applied.

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6. Choose your reducer.

Now you have to decide which temperature range of reducer you want to use in the basecoat. You don’t want to use a reducer that dries too quickly because that’ll cause the blend edge to appear course. A slower-drying reducer will allow the basecoat to lay down flat, improving your chance of an invisible blend. How do you decide? By taking into account booth temperature and humidity. Higher humidity makes the paint set up faster, just like higher temperatures do. Remember, if you’re using a downdraft booth, you have a high volume of air going over the surface of the vehicle. If painting or blending into any horizontal panel, I usually add 10 degrees to the air temperature to account for the moving air over the surface.


7. Apply the basecoat.

Once you’ve selected the proper reducer, apply the basecoat according to the manufacturer’s instructions. If you didn’t use a color-keyed primer, you should apply the ground coat now. The ground coat is just a keyed basecoat, so you should apply it just like you’d apply a basecoat.

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The purpose of the ground coat is to limit the amount of paint needed to attain coverage. A good blend uses the smallest amount of basecoat on the panels being blended. If you have a poor hiding color and you have to apply five or six coats of color to cover the repair spots, you’ll find that the panel you’re blending into will have the color across its entire length, negating the blend effect.


Apply the basecoat to the repaired areas first, always expanding each coat beyond the next. Continue applying the basecoat until all the primer/ground coat areas are covered. Remove the masking paper from the panels being blended. Tack off the panels being blended before you start extending the basecoat onto them. Apply the basecoat to all the panels, extending 2 to 3 inches into the blended panels. Continue extending each application 2 to 3 inches beyond the previous coat, until you’ve achieved a smooth blend.

Many painters make the mistake of dusting a coat on the entire panel, thinking it’ll cover any dry edge or sanding marks. But if you prepped the panel properly and chose the proper reducer, there shouldn’t be a dry edge! Remember, if you dust paint on the entire panel, you didn’t blend it.


8. Grab a coffee.

Allow the basecoat to flash off according to the manufacturer’s directions – usually 30-45 minutes. Keep in mind that the more coats of basecoat you’ve applied, the more flash time that will be required. Solvents tend to get trapped under multiple layers of paint, so give them time to escape before applying the clearcoat. A downdraft booth also causes paint to dry quickly on the surface, actually trapping solvents. It’s crucial that you let the basecoat flash off properly.

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9. Grab a tack rag.

After the basecoat has flashed, tack off the refinish areas using a tack rag designed for basecoats. Be careful that the tack rag doesn’t dig into the basecoat or disturb any metallic effect.

Why use a basecoat tack rag? Because basecoat tack rags aren’t as sticky as regular tack rags. If you use a regular one during this step, you risk the tackifier coming off the tack rag due to the solvents in the basecoat. This can cause a paint defect in the clearcoat.

10. Apply the clearcoat.

Apply the clearcoat according to the manufacturer’s directions. If blending of the clearcoat is required, use the same tapering technique that you used when blending the basecoat. Extend each coat of clear slightly beyond the previous coat to achieve a tapered edge.

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Make sure you don’t extend the clearcoat into an area that wasn’t properly scuffed. If this happens, the vehicle will end up with a peeling problem after a few months in the sun. Trust me. It’ll happen. I know.

If your paint manufacturer offers a blending solvent, apply it sparingly. Too much blending solvent will cause the clear to sag at the blended edge.

The best way I’ve found to use a clear blending solvent is to apply a very light coat just to the tapered edge of the clear. After that’s flashed for five minutes, I apply another coat of it to a 3-inch area on both sides of the tapered edge.


11. Wet sand and polish.

After the clear’s dried, wet sand and polish the tapered edge as recommended by the paint manufacturer.

Remember, blending is just another tool in helping you to achieve an acceptable paint match. Follow these easy steps, and you should achieve that acceptable match – every time.

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Mike Muir is a 10-time winner of Ford Motor Company’s Medallion Manager Award, given for customer satisfaction. He’s been in the autobody field for 26 years – the last 17 as a dealership shop manager. Muir’s also a singer, songwriter and musician. You can contact him by e-mail at [email protected]

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