Tips for Effective Touch-up
Editor's Note: This article was written by PQA Inspector Dave Lick and is reprinted with permission from the MPI (Master Painters Institute) newsletter. MPI content describes best practices for commercial, institutional, and light industrial painting.
Here’s a painter’s nightmare:
He’s just finished applying the topcoats in a shiny new office complex. One of the guys moving in the mahogany conference-room table slips, and—SMASH!—what had previously been a perfectly painted bright-red wall adjacent to a window beaming with sunlight now has a gouge mark clear down to bare drywall.
So it’s time to touch up. First, the gouge mark must be repaired with white drywall filler, which will absorb the coating at a different rate than the finished wall. And even though the finish was flat, the touch-up may remain visible because of the critical lighting conditions caused by the window.
It’s highly likely that a complete edge-to-edge repaint will be required.
Not all touch-up jobs are this tricky. But if touch-up work isn’t done properly the first time, the costs in time and money can add up. So whether the substrate is drywall, wood, steel, plaster—doors, door frames and trim, ceilings or walls—here are some best practices to assure touch-up work that is essentially invisible.
Tips for Touch-Up
It’s common in construction for surfaces that a painter meticulously coated to get damaged or marked when furniture is moved or an unforeseen construction modification is required.
The painter thought the job was finished—but the GC, architect, or owner’s representative does a walk-through and points out defects that must now get touched up.
We evaluate the quality of touch-up work by viewing the surface from three feet/one meter away at both 90-degree and 45-degree angles, in whatever the permanent lighting conditions will be. If the touch-up is not visible under these circumstances, it’s deemed a success.
Improper touch-up can lead to “flashing,” making the repair area painfully obvious due to changes in coating absorption or application method.
When touch-up is not done properly, the coating defect “flashing” will occur. Flashing describes the non-uniform appearance of the coating due to noticeable variations in the color or gloss, produced by a variation in coating absorption by the surface or changes in application method (e.g. brush to roller).
Top 2 Rules
We know that the higher the gloss and/or deeper the color, the harder it is to touch up successfully; in fact, it may be impossible. Finishes from flat to eggshell (MPI Gloss Level 1, Level 2 and, in some circumstances, Level 3) may be effectively touched up as long as you observe these “like over like” requirements:
If the surface was rolled with a 10-mil nap roller, a 10-mil roller must be used for the touch-up. The roller used for touch-up can be smaller, but the nap must be identical. If not, flashing is virtually certain to occur.
Far too often, we see this rule ignored: A well-meaning worker will use a brush or foam-tipped applicator to touch up small defects on a rolled wall. The difference in the finish texture will be painfully visible.
Brush marks from a touch-up will be plainly visible on a rolled wall.
Touch-up must also be done with the same care and technique as the original application. Frequently we see touch-up coats slopped on, which can make the problem worse. Furthermore, effective touch-up may also require multiple coats.
Sanding the Surface
When touching up damaged surfaces, note that if the mark changes the surface profile (makes a dent, for example), the surface must first be made level by sanding. Otherwise the best touch-up work will still be visible.
It’s a common error in touch-up to paint without first sanding the surface. In theory, touch-up does not require sanding if the substrate has not been disturbed, but in our experience, almost all marks include some kind of surface damage.
For drywall surfaces, filler may also be required. And if a damaged drywall area is greater than three square inches, it must first be coated with a drywall primer/sealer such as that approved under MPI #50.
If the touch-up craftsman failed to observe the “like on like” rule described above and used a brush to touch up a rolled wall, the touched-up area will have brush marks that will telegraph through any additional coats of touch-up material—even if the repairs are done with the same tool as the original finish.
So fixing the touch-up must begin by sanding off the brush marks.
Dealing with Sprayed Surfaces
So when is it unacceptable to touch up a surface? Any surface that is sprayed with a semi-gloss or gloss finish (MPI Gloss Levels 5 or 6) cannot be effectively touched up.
For sprayed surfaces that are lower gloss—especially ceilings or other areas that can’t be viewed at close quarters—it’s possible to touch them up with HVLP spray equipment.
We often see ceilings coated with dryfall that are later modified with a new pipe or fixture; sometimes, these can be successfully touched up with careful spray work.
Doors, on the other hand, can present a special challenge. Doors are often airless-sprayed with a semi-gloss or gloss finish. In such cases, a mark on the door will require a complete recoat, edge to edge. And the time required to rectify the problem will multiply if there are multiple doors.
Here’s an example: One side of one door gets marked while the carpet is being installed. At this stage, spray painting for touch-up will not be permitted on site. Nor will the owner allow doors to be removed and taken off site to be sprayed. So, not one but both sides of the door need to be re-finished edge to edge by either brush or roller.
Now, the rolled surface will have a different stipple and color than a sprayed door. So if the marked door was part of a double set of doors, or if there are additional doors adjacent to (or clearly visible from) the original door, these will also need to be re-finished from edge to edge.
The inspector was on a project with a vast array of ornate wood trim and molding that was spray-finished before and after installation with a perfect airless-sprayed satin finish.
However, during the final construction phase, some parts of the trim were damaged and marked. The painter didn’t heed the “like on like” rule and touched up the damaged areas with a brush. Ouch! The repairs could now be seen from across the room.
The irate owner called in the paint inspector for help.
His solution? Tape the wall areas around the trim corner to corner, cover all floors and adjacent surfaces, and sand out the brush marks. Then, meticulously re-spray the damaged areas with an HVLP system that offered the lowest possible pressure with maximum control.
The resulting repair was a success, but at a cost of time and money that neither the painter nor the owner had ever anticipated.
The moral of the story?
If touch-up is not done correctly to begin with, the time and cost required to fix the problem can escalate quickly. Furthermore, whether a surface can be touched up at all depends on a range of factors, including the finish’s gloss, color, method of initial application, and location—especially where critical lighting is involved.
And be warned: What worked in one area won’t necessarily work in another.