Coatings World - May 2011

sylvania, Maryland, and West
Virginia. It became a PPG Plat-
inum Distributor in 2006,
shortly after electing to carry
and supplies for the mechanical side of
the automotive aftermarket industry.
Currently, it is heavily involved in assist-
ing its PPG Refinish collision shop cus-
tomers in the conversion to PPG
waterborne products.

The PPG Platinum Distributor program began in 1995 as a loyalty and support initiative for PPG single-line distributors with the ultimate goal of providing exceptional service and benefits for PPG Refinish customers. The pro-

Letter to the Editor

In the January 2011 issue of Coatings World on page 25, Zinsser introduced their Bondz Maximum Adhesion Primer. They claimed that Bondz has eight times better resistance to wet adhesion per ASTM D2486 and D6900 compared to XIM UMA.

ASTM D2486 is a test method for Scrub Resistance of Wall Paints.
Per this test method, ASTM says “interior wall paints often become
soiled, especially near doorways, windows, and in work and play areas.
This test method covers the determination of the relative resistance of
different wall paints to erosion when repeatedly scrubbed to remove
the stains during the life of a paint.”
At XIM we asked ourselves, “What does a scrub test for interior
flat paints have to do with adhesion to tough-to-paint surfaces or
even exterior durability?” Zinsser said if you scrub Bondz it has eight
times better scrub resistance than UMA. In our experience, high ad-
hesion, water-based exterior primers designed for wet adhesion
have relatively low scrub resistance. In fact, the higher the wet ad-
hesion the lower the scrubs.

Think about it this way. Would you apply an interior wall primer with high scrub onto exterior ceramic tile? Of course not. It would most likely fail. XIM does not focus on scrub resistance. If Zinsser is addressing wet adhesion to a wide range of surfaces, it is XIM’s opinion that this is the wrong test, the wrong assumption and the wrong conclusion. In this case they would be better off using the ASTM D3359 test method for measuring adhesion, especially if they are addressing exterior products with wet adhesion.

Another test where Zinsser claims that Bondz out performs XIM UMA is ASTM D6900, wet adhesion of latex paint to a gloss alkyd enamel using a scrub machine. This test is designed to measure the ability of a coating to resist removal from the surface beneath by scrubbing. While this test is closer to an adhesion test, it is still focused on scrub resistance.

XIM testing comparison Comparative Test #1

Glossy ceramic tile:

1- Clean it well (we do not want to paint grease and dirt);

2- Apply the XIM UMA and the Zinsser Bondz side by side;

3- Let each primer system dry and cure;

4- Scrub with a razor knife so water has access to the substrate via this
“paint break”; and
5- Expose to water.

As demonstrated in a very simple, but real test, exposure to water and a glossy tile, the Bondz primer peels while the XIM Bonder does not. After water contact, the Bondz primer can simply be pushed loose with finger pressure.