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Surface Stories: When “clean” means not so clean

When it comes to preparing raw materials for adhesion in manufacturing, optimizing the level of surface preparation is directly related to achieving the highest quality final product.

Under-preparing a surface, or over-preparing a surface both mean sub-par adhesion when it comes time to bond, coat, print, seal or paint.

The first story in our new series, Surface Stories, pertains to over-processing, when a recent customer in the aerospace industry was sure they were helping to make their aluminum surface “cleaner.” The Surface Analyst, however, showed otherwise.

The aerospace manufacturers’ standard surface preparation process was to measure the surface using the Surface Analyst prior to processing, which resulted in a water contact angle in the 70’s. This measurement was not satisfactory for strong and consistent bonding, so further treatment was necessary.

The next step in their process was to abrade the surface, a highly effective and common process for better preparing aluminum surfaces.

The sanding step in their process dropped the water contact angle down in the 40’s, and according to the manufacturer’s standard procedure, this measurement range had been deemed satisfactory for strong bonds.

But what about the debris left on the surface resulting from sanding the surface?  The manufacturers next step was to wipe the abraded surface with a “chemically clean” rag to remove the sanding debris.

However, after this step, the WCA measurement would shoot back above the 60-degree mark--outside of the process’ acceptable range.

Despite of the manufacturers thorough sanding and cleaning process, the customer had still been experiencing bonding failure somewhat regularly in their operation, and so a big question remained.

The answer, came by way of the Surface Analyst.

Despite the rags being labeled as clean, WCA testing with the Surface Analyst clearly showed an increase of the surface after wiping back above the 60-degree mark. The rags themselves in fact did contain chemical contaminants.

What was first thought to be helping, was actually making things worse.

This was of course, no fault of the customer, but would not have been possible to know without the help of the Surface Analyst. But what about the business implications?

Be sure to subscribe to this blog for additional updates in the future related to your application and to see how this story ends.

For immediate information about BTG Labs and how the Surface Analyst can be used in your operation, reach out to us using the the Contact Us form at the bottom of this page.

The Truth About Your Process, Lies Right on your Surface