1. How stable are the colors of ceramic color standards? High quality ceramic color standards are durable, stable and cleanable. For more than 40 years metrologists and color scientists have preferred ceramic color standards.

2. How much does a ceramic color standard change in 1 year? With high quality ceramic color standards no measurable changes in color or appearance occur spontaneously.

3. How much does a ceramic color standard change in 5 years? No changes in color or appearance occur spontaneously, but ceramic glazes are subject to physical scratching and to etching following exposure to strong acids or alkalies. Such changes are not reversible. For more information consult the maintenance manual.

4. Are any long-term color stability data available? Dr. Art Springsteen (Avian Technologies) has re-calibrated individual sets of Ceram Series II tiles annually for more than 5 years. According to him no measurable changes in color or appearance occur provided that ceramic color standards are properly handled, maintained and stored. Based on our own stability measurements since 2005, we agree with this conclusion.

5. Are color standards affected by changes in ambient temperature? The color of a ceramic tile changes measurably and reversibly with changing temperature. During 2007 Dr. David Wyble (Munsell Color Science Laboratory) measured the "thermochromism" of our original tile sets. He concluded that the thermochromism exhibited by our color standards is similar to that of comparable Ceram Series II tiles. This finding is not surprising since both sets of tiles are manufactured using commercial glazes and ordinary firing procedures. (Note: See FAQ 8.)

6. What can cause the color or appearance of a ceramic color standard to change? If color standards are handled or stored improperly, short-term reversible color changes can occur. For example, if the user doesn't wear clean, lint-free gloves, color standards can become soiled in a single work session. If the optical surfaces are not damaged, soiling usually can be removed by careful cleaning. Ceramic glazes are subject to scratching and chemical etching. Color standards that have been physically damaged cannot be restored.

7. What materials and procedures should I use to clean color standards? During 2009 we introduced a Cleaning Kit for which inexpensive refills are available. Consult the instruction manual or the maintenance manual for additional information.

8. What are the differences between Ceram tiles and Mt. Baker Research color standards? Ceram Technology Ltd. and the original manufacturers of our ceramic plates use ordinary commercial glazes and firing procedures. Therefore, the surface characteristics and many of the colors are similar. Although our color standards are technically equivalent to Ceram tiles, we offer reduced translucency color standards as well as many additional colors.

Our color standards offer the widest color gamut available in the international marketplace. The two photos that appear below show our reference collection of Ceram BCRA Series II tiles and CERAM Series II special chromatic and achromatic tiles. The areas of glare show that two edges of each Ceram tile exhibit pillowing and edge pullback (thickening of the glaze near the edges). The resulting deviations from flatness may cause significant measurement errors. (Note: See FAQs 12 and 13 below.)

Ceram Series II tiles plus White & Black.

Special Ceram Chromatic & Achromatic tiles. (Bottom Row, Ceram White tiles.)

9. Do ceramic color standards exhibit surface defects? All ceramic glazes exhibit minor surface defects ("micropits"), which are caused by out-gassing during kiln firing at high temperature. With high-quality color standards these defects do not interfere with spectrophotometric measurements.

10. Are Mt. Baker Research color standards flat? To eliminate edge defects and improve flatness we precision machine color standards from the flat central portions of nominal 6-inch ceramic plates. Our color standards do not exhibit pillowing, curved edges or edge pullback (thickening of the glaze near the edges). Our color standards are engineered to achieve effective optical contact with the full range of available portable and benchtop spectrophotometers.

11. Why is surface flatness important? Unless the optical surface of a color standard is flat to within 0.001 inch, with many laboratory spectrophotometers the color standard cannot contact the sample stage across the entire optical surface. This problem leads to measurement errors that vary from instrument to instrument depending on the design of the sample stage.

12. When is it necessary to calibrate individual color standards? Normal micropits and variations in glaze thickness and composition lead to measurable differences in color between individual color standards that are supposed to be identical. Individual calibration is the only way to mitigate this problem.

13. How often should color standards be calibrated? We recommend annual re-calibration to users who are concerned about stability. Because our color standards are inherently stable, annual calibrations serve to check the user's procedures for handling and storage.

14. What is the definition of traceability? Each instrument, such as an X-Rite ColorEye 7000A ("CE7000A"), is supplied with a calibrated white tile that is used during initialization. The reference calibration data for this tile reside in the firmware of the instrument. These reference data are used to scale measured spectral reflectance data in order to compensate for calibration error.

Because the reference calibration data for a serialized X-Rite white tile are traceable to NIST, both the white tile and the CE7000A are said to be traceable to NIST. However, strictly speaking color standards and instruments are not traceable. Traceability describes certified calibration data measured using procedures approved by ASTM and other international standards organizations. The certified data are traceable to the standards laboratory that calibrated the reference tile on which scaling is based. (Note: See FAQ 15 below.)

Traceability to NIST may be achieved by using freshly-pressed polytetrafluoroethylene ("PTFE") powder as the scaling reference. Because the optical surface of this color standard is unstable, this method is unsuitable for use with the diagnostic procedures recommended here. (Note: See the references on traceability for more information.)

15. What is the definition of scaling? In color metrology the "ratio" or "scaling" method is used during measurements of spectral reflectance (or radiance) factors ("SRF"). Each measurement of a sample is accompanied by measurement of a calibrated reference color standard for which the absolute SRF data are accurately known. An independent standards laboratory such as NRC or NIST should provide these reference calibration data.

Following each measurement the wavelength-dependent SRF data output by the instrument are divided by the corresponding measured values for the reference color standard, and then multiplied by the known absolute SRF values for this reference standard. If the reference color standard has been calibrated at a certified laboratory such as NRC or NIST, this procedure provides the basis for traceability as well as a determination of the absolute accuracy of the test instrument. (Note: See FAQ 14 above.)

16. Where can certified, traceable calibration services be purchased? The staffs at Mt. Baker Research and Avian Technologies are trained and equipped to provide certified traceable calibration services. In the (d/8°) specular-included and (d/8°) specular-excluded geometries, the abridged spectrophotometers available at Mt. Baker Research measure the wavelength range 360 - 1,050 nm with a pitch of 5 nm, or 360 - 750 nm with a pitch of 10 nm. Our certified spectral reflectance measurements are traceable to NRC or NIST.

Avian's dual-beam, scanning instruments can provide traceable measurements from the ultra-violet through the visible to the near-infrared with a wavelength pitch of 1 nm. Government-sponsored laboratories also offer certified calibration services, but they are much more expensive. Contact NRC or NIST for more information.

17. Can Mt. Baker Research produce color standards in custom shapes and sizes? On a special-order basis we can produce precision machined round ceramic color standards or geometric shapes with straight cut edges. If defect-free edge quality is not required, we can use less expensive cutting methods to manufacture standards of virtually any shape with maximum dimensions of 6 inches.

18. Does Mt. Baker Research offer color standards with sealed edges? We have developed special Delrin holders and a mounting procedure that uses silicone resin to seal all 4 edges of our 2x2-inch square color standards.

19. Can Mt. Baker Research produce custom holders? We can manufacture custom holders in different sizes and with different size positioning wells. Custom holders may be subject to special pricing or to a minimum order quantity. We provide the design work free, but complex designs may require an additional setup fee at our machine shop. Custom machining typically requires 6 - 8 weeks ARO.

20. How may I view the images on this website with accurate color? All of our images are color managed. To view them with accurate color you need to do two things: (1) Use a color-managed computer display. (2) Use color-management-savvy viewing software. (Note: Microsoft Office software does not support color management.)

On Apple Macintosh® computers the Safari® web browser is color-managed, and Mac OS X automatically color-manages flat-panel displays. As another option, you can download the image files to your computer and view them on a color-managed display with Apple Previewer®, Adobe Photoshop®, or Photoshop Elements® software.