Painted Surfaces; White Paint; Red Paint; Comparative Test Results With And Without Grinding - Thermo Scientific XL2 User Manual

Table 1. Comparative test results with and without grinding
Test Results with Ground Surface
Test Results with Unground Sur-
face

Painted Surfaces

White Paint

Red Paint

Thermo Scientific
0.67
0.61
Paint is a mixture of several items that are combined into a liquid which is applied to the
surface of materials such as metal. Once applied this liquid dries with time and adheres to the
surface of metal. Paint is used to protect or decorate the metal item. Paint can also be used to
identify or mark the metal during the manufacturing process.
Components of paint are divided into classifications of pigments, binders, solvents, additives
and fillers. The inorganic elements in pigments will contribute to increases in displayed values
for those elements if paint on the metal surface is not removed prior to testing. Be especially
careful of the presence of heavy elements, which can also act to shield x-rays from lighter
elements in the metal sample.
The following is a list of some of the most common components of paint:
• Antimony (Sb)
• Lead (Pb)
• Titanium (Ti)
• Zinc (Zn)
• Cobalt (Co)
• Iron (Fe)
• Lead (Pb)
• Green Paint
• Chromium (Cr)
An experiment was conducted to determine the effect and severity of surface problems on
XRF results. Results from analyses of a 1541 alloy steel sample are shown below, before and
after surface grinding. The sample had painted markings, of light to medium thickness, on
the surface, as well as light rust. Note the change in titanium, zinc and cobalt levels after
surface grinding.
0.089 0.070 0.033
0.178 0.081 0.033
5
Common Operations
Metal Sample Prep
0.039
0.514
Niton XL2 Analyzer User's Guide 49