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Best Practices:
When the Color Makes the Paint Fail

Tuesday, February 25, 2014

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Here’s a scenario known to frustrate all parties on a paint project—and although this incident involved new construction, the same problem can surface on a maintenance repaint:

  • The architect designed a school—the latest of many done by the firm.
  • The specification writer prepared the detailed spec.
  • The color consultant released the color schedules. 
  • The general contractor had the project nearing completion.
  • The paint contractor prepared to start application.
  • The paint store tinted the paint order to the selected colors.
  • The specified paint was applied.
Colorful house
©iStock / paulprescott72

Today's bold colors can affect paint performance. Specifiers and applicators should bone up before working with them.

  • The students came to school.
  • The surface marked excessively, prompting students to further mar the finish.
  • The school board demanded answers.

What happened? Who is responsible?

Not My Fault

The architect and the specification writer are approached first. They respond that the specified semi-gloss high-performance architectural latex (a product approved under MPI #141) had been used with considerable success on school after school after school with no such problem. In fact, MPI’s High-Performance Architectural Latex standards (MPI #138, #139, #140, and #141) are designed to be its highest-performing interior latex standards.

The painting contractor is approached next. He responds that he followed the spec and purchased the specified semi-gloss latex coating, tinted to the color selected.

The paint manufacturer is up next. He insists that the proper material was supplied and tinted with universal colorants (which are now increasingly zero VOC) to the color chip selected by the color consultant. The paint batch was checked at the lab and found to meet spec. A drawdown was made, and the color was found to be within the acceptable tolerance range.

The Challenges of Deep Tones

So what happened?

The key to the answer is that the semi-gloss latex required the addition of about 15 ounces of universal colorants to the base to achieve the desired color.

Too much of most universal or glycol-based colorants can have an adverse effect on a paint's properties, including a reduction in abrasion and mar resistance; a drop in sheen from semi-gloss to low gloss; delayed drying time (sometimes twice as long as expected); and poor hiding that can mean extra coats.

Purple Building
MPI

Many of the deep colors now in vogue may need a heavy addition of pigments that can hamper paint performance.

So, using deep colors can affect paint performance as well as the project’s ability to meet schedule, budget and aesthetic requirements. Since deep hues are in vogue with today’s design community, here are guidelines for successfully specifying and applying these materials.

How Tinting Affects Paint Performance

Deep colors affect paint performance in two ways:

  • Color pigments are softer than white pigments; and
  • In-store colorant systems can change the characteristics of the paint.

Color v. White Pigments

A good white paint typically has greater resistance to abrasion and marking than deep tints and accent colors do, because the clear bases used for deep colors lack the titanium dioxide (TiO2) that makes white paint white.

But TiO2 is not just a whitener. It’s harder than most color pigments. That hardness makes a big difference in the paint’s resistance to impact and marking. So a paint film loaded with TiO2 will be more robust than one loaded with soft color pigments.

The Nature of In-Store Colorants

The vast majority of colorants that a store uses to tint your paint consist of powdered pigment dispersed in a liquid that contains glycols and surfactants (even with zero-VOC systems). So adding substantial quantities of material (e.g. 15 ounces per gallon) that will become a permanent part of the paint film can, for all practical purposes, change the paint formulation.

One readily noticeable difference may be a substantial increase in dry time, due to all of that non-drying glycol/surfactant being added to the can. (Note: This is not an issue if the paint product uses a resin-based colorant system.)

Factory-Made Colors

One alternative is to use factory-made colors. Back in the day, it was common for paint stores to carry “stock” colors. A customer could walk in and find black, red, or other basic shades right on the shelf in cans that came straight from the factory.

When deep colors are produced at the factory, the colorants are added as dry powder milled directly into the paint; no glycol-containing dispersion vehicle is required. In addition, the paint manufacturer can optimize the formula by adding additives and extenders to strengthen the film and increase hiding.

So a paint company’s formulation for factory-produced “black interior latex” will always offer superior hiding and performance than a store making black paint by adding tint to a clear base.

Paint
©iStock / ozgurdonmaz

Matching a color made by another manufacturer can be problematic.

The industrial maintenance paint industry still produces plenty of colored paints right in the factory. But not the architectural coatings market: We now expect paint suppliers to offer countless custom colors, so stores are understandably reluctant to have factory-tinted stock on hand.

In this inspector’s experience, if you order exceedingly large quantities of paint, you can get the product factory-tinted—but orders of less than 300 gallons or so will end up getting tinted in the store.

Matching Another Manufacturer’s Color

The problem can be exacerbated when a paint store is asked to match a color chip from a different manufacturer.

We realize that this happens all the time, but be advised that a paint company designs its bases and tint systems to produce its own color system—not that of a competitor. Trying to match another company’s deep colors may require adding excessive tint base, leading to all the problems described above: a drop in sheen, delayed dry times, weak hiding power, and reduced resistance to burnishing and marking.

Most store reps running the tint machines are aware that adding excessive colorant may degrade the paint's properties and still not precisely match the competitor’s chip. However, when an anxious customer asks for more colorant because the shade “isn’t quite right,” the rep understandably finds it difficult to say no, and the customer generally gets his way.

Other Issues

The nature of the pigment can also affect performance. For example, some color systems create darker browns by adding yellows in the tinting process. On a building exterior, southern exposure walls that are exposed to more UV light may exhibit excessive fading.

Other color systems, however, may obtain the same dark brown with alternative color mixtures or pigments, and the result is a very colorfast finish.

Tips for Applying Deep Tones

A well-meaning contractor may believe that deep- and accent-colored paints require four, five or even six coats to achieve hiding. Here are options to avoid this trap.

  • Ask if the paint supplier can recommend a primer or intermediate coat that will provide optimal hiding underneath the color specified.
  • Learn which undercoat colors enhance the hiding power of which topcoat colors. For example, if a yellow topcoat is specified, the area should first be undercoated with an absolute pure white. Avoid any shadowing or gray tone, which can telescope through the yellow. Red finishes are best undercoated with a brownish red, which has more robust hiding power than pure red.
In either case, it’s critical to first achieve a totally uniform base color before applying the deep tone accent color.
  • Follow the manufacturer’s instructions on dry time between coats. Applying a new coat before the previous coat has completely cured can compromise hiding power. Picture this: You’re rolling out a brilliant, deep red, but you allow only “dry to touch” time before applying the next coat. The new coat will re-wet and soften the previous one, causing it to get picked back up in the roller, so you end up removing some of the previous coat while applying the next. That's not conducive to good hiding!
  • Some paint manufacturers now offer color tint bases in basic colors (e.g. red, yellow, and blue). When a store tint machine starts with a base that has the initial pigmentation built into the base, fewer ounces of colorant will be needed to achieve the desired color.

Repainting Non-Uniform Surfaces

Sometimes we see repaint projects where the surface is already discolored with spots in a different color (for example, a green wall is touched up with blotches of yellow patching compound).

The owner now wants a color change to orange. If the painter tries to apply the orange intermediate and topcoat directly over this wall, the result will be a washed-out orange over the yellow patching material, and a muddy orange over the green areas.

Drywall
MPI

The existing wall has spots of yellow drywall filler on the gray-green finish—a nightmare for repainting with a deep tone if the wall is not properly undercoated first.

It could take many more (nine or 10?!) finish coats to achieve a uniform appearance on this wall than either the painter or facility manager had planned. And even then, the underlying difference in color may still telegraph through. The solution is to first apply a suitable primer/undercoat to create an absolutely even all-over color, using the guidelines above.

Tips for Specifying Deep Colors

We often see specifications that call for one coat of primer, plus one or two coats of intermediate/topcoat. However, as we've discussed, this may fall far short of what’s needed to achieve suitable hiding and the desired finish with deep tints and accent colors.

So we make sure our specs also include the phrase, “Deep and accent clear-base colors may require 1-2 more coats to achieve the proper hide.”

If the right undercoat/primer is strategically chosen to complement the intermediate and topcoat, and the undercoat/primer is carefully applied to achieve a totally uniform appearance, suitable hiding may be achieved with two coats of primer and two coats of finish.

The key to success is to minimize surprises. Do a test patch first. The time to realize you have a problem should be after the second coat, not after the sixth.

Know the potential impact of your color choice before the project starts.

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.

   

Tagged categories: Architects; Architectural coatings; Color; Color trends; Master Painters Institute (MPI); Pigments; Specifiers

Comment from Gary Janezic, (2/25/2014, 8:11 AM)

Don't forget that all acrylic latex paints are more durable than vinyl acrylic interior grade paints. Select an all acrylic for durability on interior surfaces. Also, question whether a dark color is necessary to avoid high colorant loading which will reduce a paint film's durability


Comment from Kent Clow, (2/25/2014, 9:23 AM)

No matter the color or finish, the final look comes down to the initial prep work. Uneven drywall mud or hole patching will telegraph through the primer and topcoat and leave an unshightly area. Also, be sure to prime all fresh drywall. If you're patching an area, prime the new drywall and mud. After drying prime the whole wall to ensure uniformity of the finish coat.


Comment from Jeffrey McIntyre, (2/25/2014, 1:48 PM)

The pigments used on exterior applications are critical to the success of deep / bright color choices. The elimination of bright heavy metal pigments such as Cadmium (Red), Molybdenum (orange) and Chrome Yellows has created fading issues. The Organic pigments used to replace these durable heavy metal pigments are very susceptible to UV degradation. This is often exacerbated by the tint formula if it contains Inorganic pigments, especially TiO2. For example, the surface layer of red organic pigment will degrade but the surface layer of TiO2 will remain causing a rapid fade to a Pastel Pink. Another issue is with Dark colors such as Hunter or Forest Green that contain Carbon or Lamp Black. The black pigments absorb Infrared (IR) light and the heat generated accelerates the breakdown of the resin binder in the paint. The chalking resin will create a pastel look on the dark pigments below the surface. The design professionals need to choose bright exterior colors based on the formula components. When organic pigments are used for an exterior bright/deep color you must pick a color that does not contain any white (TiO2) in the formula. Or even better, choose yellow or red colors obtained using inorganic pigments like Red Oxide or Yellow Oxide which have excellent UV stability.


Comment from Lance C Futcher, (2/25/2014, 5:52 PM)

Wow, just recently we had a problem exactly as you described here in a school in Melbourne (Australia). The difference was that here they had used a Low Sheen Acrylic in a strong dark blue colour which burnished excessively instead of using a semi gloss acrylic, but now I have a far better understanding of what contributed to the problem. Thank you for the article. Just one point if I may, here we recommend that under dark colours the contractor applies a coat of grey undercoat (primer) varying from the great deep grey depending on the final colour rather than a version of the colour .... Any comment on that system?


Comment from Tom Schwerdt, (2/27/2014, 10:17 AM)

Gary - Acrylics are in general more durable with regard to UV/sunlight, but vinyl/acrylics are in general harder and more wear/scrub resistant. Vinyl/acrylics definitely have their place for indoor paint where you expect moderate traffic/rubbing/marking. They can also be a better choice where you will have long-term contact between an item and the painted surface (such as a painting on a wall) - the vinyl/acrylic is less likely to stick to the frame of the painting. With either one, it's still good policy to allow a good, long cure before putting objects in contact with the paint.


Comment from Mark Ryan, (2/28/2014, 9:46 AM)

I bet if you attend the D+D 2014 in Cincinnati you'll hear about ways to avoid these issues and have durable color.....


Comment from David Lick, (2/28/2014, 1:21 PM)

Thanks for all the feed back. The story of the school with the deep colours is not isolated to Acrylics based resins. I have inspected work that has had even Alkyd based finishes with excessive burnishing tendencies because of deep colours. In answer to Lance Futcher from Melbourne. Yes the slightly coloured grey backgrounds do work well under deep tone colours. Also the lower the gloss the higher the Pigment Volume ratio (PVC). The danger of excessive burnishing increases as the gloss drops. In regards to hiding, the real key is to have a very uniform undercoat with no blemishes or discolourations that could possibly telegraph through the finish coat. At home here in Western Canada, we have seen good results applying the manufacturers that have primary coloured bases.


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