Performing Paint Touchups Like A Pro
At some point your beautiful paintwork may get damaged, be it chips, a scratch or worse. When colour sanding and polishing, there is always the possibility of buffing through. If this occurs on a large uninterrupted area such as a quarter panel, it may not be practical to paint the entire roof and both quarters to get a seamless repair for a small imperfection.

If you have a custom, tri-coat paint job, it may also be difficult to match the colour accurately on a section without blending. Blending is the gradual paint transition from the repair area into the surrounding existing finish. Different materials require different techniques. When you first paint your car, remember to put aside a small amount for touchup and record what color you used. In a custom finish, you will need to record the base color, mix ratios and number of coats used over it, to get the same shade and effect. An excellent blend job should be impossible to detect. If you become proficient at blending, you will be able to repair with a colour that is off quite a bit to the original as our eyes and minds can’t detect a gradual colour variance over a large area.

When doing small repairs it is necessary to properly “featheredge” the surrounding paint and to seal it with a good catalyzed primer. Featheredging is the sanding of the paint in broken areas till it forms a smooth and gradual transition, in effect layering it back so that it is barely felt and no sharp edges. Orbital sanders are particularly good for featheredging. Remember to degrease any repair areas before you begin any sanding. When priming over featheredged repairs extend each coat a little farther out each pass so you do not build it high in the same spot. This will help prevent cutting through the adjacent paint when sanding (which could swell when painted if cut open).

Good masking is critical to achieve an invisible repair. If there are defined edges, as with a door, the masking is straightforward – mask the adjacent panels, cover the rest of the vehicle and paint the door. Plastic sheeting is fine for covering large areas from overspray however do not use it immediately adjacent to where you are painting. Paint can blow off the plastic as it dries up between coats, use paper instead which will absorb the overspray. Always try and use an automotive grade masking tape, this will save you a lot of aggravation as regular masking tape is thinner and less adhesive and a nightmare if it gets wet. If you are doing a small blow-in on an area you don’t wish to paint completely you need to mask a bit differently. Let’s use a quarter panel as an example where there is no seam going into the roof (which in this case doesn’t need to be repainted). Mask as normal around the quarter at the trunk and door, cover the roof, but loosely paper the roof pillar with no tape on the painted area. This will allow you to blend your paint into the pillar without ending up with a defined edge. Rolled tape masking is another method pros use to get a “soft” edge on a blended area. If for example there is a bodyline you wish to blend up to, place wide tape over the body line with half extending into your blending area then pull it up and bend it back so it is rolled along the body seam (you will need to use some tape to hold it rolled back). This should be setup to be pulled off while the paint is wet, preventing a visible defined edge. Make sure when you are prepping and masking for a blow-in, you give yourself lots of room to blend out your paint.

The type of finish you have will determine how to prepare the area for a blow-in:

- With single stage paints that are not clear coated, degrease the panel and sand only the repair area and a bit out, then buff the rest of the panel with rubbing compound.

- For most acrylic enamels, reducer or color blender can be used to melt-in the paint blend to the compounded area.

- For single stage urethane colors, you will need urethane blending solvent (sometimes called fadeout thinner). Start by mixing your paint as normal and applying a few coats to the repair area extending it past a bit each pass. When you have coverage, mix the blender 50/50 with the remainder in your gun and blend this out, wait a few minutes and add more blender and spray out further and finally finish with straight blender and low pressure to melt out the last bit of overspray. The next day you may need to compound the blended area to make it totally disappear or melt in.

- Metallic colours can be harder to blend and may look different at the end of your blend from it being sprayed drier and from an angle causing the metallic to orient different there. Metallic colours tend to look lighter when sprayed light and darker when sprayed heavier. There are a couple of techniques to solve this, one is back blending where you blend out then start from the edge of your blend and blend back into your repair. Another popular method is after applying your last colour coat, hold the gun back a couple of feet and cross coat out at full trigger down the panel to give a very even metallic disbursement and hide the edge of your blend. The droplet method uses very low pressure with a full trigger on the blended edge to orient the metallic.

- In acrylic enamel, keep adding reducer on the final coats to dilute the colour making it easier to blend out.

- In single stage urethane metallic, mixing in urethane clear on the last coat works well.

- For most base clear repairs, fine sand the entire panel, spray in the base colour on the repair area gradually blending out a bit further each coat then clear the whole panel for an indistinguishable repair (this is one of the pluses of base clear). If the area is too large to clear, then blend the clear as you would the urethane, you may need to compound this the next day to make it perfectly smooth.

Multistage colors are blended as they were applied – in stages and require a lot of patience to do satisfactorily. One of the secrets to successfully blending custom colours is to dilute them with clear resin so they blend more gradually. Blend as you would basecoat but more gradually in each stage. Some colours (like coloured pearls over white) are very difficult to blend invisibly as the pearl can orient different at the edge of the blend causing a visible halo from an angle similar to a metallic colour. If you can’t blend invisibly using the techniques for a metallic, you may need to spray the panel completely, checking after each coat by lifting the adjacent masking till it matches.

Touchup guns are very handy for small blow-ins as they spray with a smaller fan and at lower pressure cutting down the blend area and overspray when compared to using a regular gun. With a little practice using the techniques outlined here, you should be able to touch up like a pro.

John