Tuesday, April 17, 2012

Surprisingly Simple Suggestions for Gloss Conrol of Semi-Gloss Paints

Factors for Gloss Control of 2-Part Semi-Gloss paints.

Two-part epoxy and urethane mil-spec finishes with semi-gloss levels of gloss are especially tricky to get correct and consistent gloss readings from because the gloss range for this class of paint is relatively wide, 15 to 45 degrees of gloss for urethanes like Mil-PRF-85285, and 15 to 30 degrees of gloss for epoxies like Mil-PRF-22750. Any slight variation of key variables can change the gloss dramatically.  Here are two of the most important variables to control to get consistent and correct gloss readings:
Homogeneous Part A.  Shake Base Thoroughly.

Shake base for at least 5 minutes on a paint shaker

A paint shaker should be used for preparing the Part A of the paint for mixing and use.  Some of these 2-Part paints are heavily pigmented and the pigment and the flattening paste tend to soft settle.  By agitating the Part A’s for at least 5 minutes all soft settling and large paint particles will go back into solution and assure a smoother paint job and a homogeneous mix resulting in consistent paint properties including gloss.  The flattening paste must be consistently dispersed throughout the gallon, otherwise you can get high gloss from the top of the gallon and then low gloss from the bottom.

Check bottom of Part A can with stir stick for settling.

After shaking for at least 5 minutes and before mixing the two parts together check the bottom of the Part A container with your stir stick to make sure there is no sediment on the bottom or in the corners of the can.  If you find sediment this means that the can must be shaken or stirred for a longer period of time.

Mix Ratio. Very Important.
Check for the proper mix ratios (See the Product Information Sheet & the Product Label)

Mix ratios are always stated as parts per volume.  So, for example, a 3 to 1 mix ratio means 3 parts of Part A to 1 part of Part B by volume and the measurements must be accurate.  Most Part B’s of 2-part paints are full gloss materials so that even a slight mistake in the mix ratio will quickly change the gloss reading of your final paint job. 

For mixing less than full containers a mixing cup with gradations and/or a mixing stick come in handy to get the ratios correct and accurate.  Accuracy in measuring is important and will insure that the paint dries properly, and has the stated gloss, and will insure that the coating develops full performance properties.

To view AeroCoat's complete line of epoxy and urethane mil-spec topcoats click on AeroCoat's Stocked Products List.

Dick Creek
AeroCoat Source, LLC