ENGINEERED PAINT BOOTHS & FINISHING SOLUTIONS
Published

Pigment to Binder Ratio Calculation

For my percent ash value the formula reads: % ash value = ((100% -% moisture of sample)/%NV) × 100. The problem I encounter is that I’m unable to figure out the percent moisture of sample. Is there a formula I’m missing?

Share

Q. I am a paint chemist. I work in a lab at a coatings company and am currently working on the pigment to binder (p/b) ratio of one our paints. But when I come to the formula to make my calculation, I’m having a little bit of trouble. For my percent ash value the formula reads: % ash value = ((100% -% moisture of sample)/%NV) × 100. The problem I encounter is that I’m unable to figure out the percent moisture of sample. Is there a formula I’m missing? R. H.

 

A. I was a paint chemist once, but I haven’t done those calculations for 40 years. I still feel your pain, though. If I understand your question, the answer is, you must measure the percentage of moisture in your pigment to make your calculation. The formula you are missing is: The weight of the untreated sample - the weight of the dried sample = the weight of moisture lost during drying. Use this weight to calculate the percentage of moisture and use that in your formula.

I also suggest you look up ASTM D 280, Hygroscopic Moisture (and Other Matter Volatile Under the Test Conditions) in Pigments. The D 280 standard gives two methods. Method A is for pigments that do not decompose at 110°C. It involves weighing a sample, driving off the moisture by heating and then re-weighing. Method B is for pigments that decompose at 110°C. It involves weighing, desiccation and re-weighing. From the difference in weights of the treated and untreated samples you can calculate the value for percentage of moisture you need for your formula. I would like to give you more details, but my ASTM books are a bit out-dated. I’m sure you have access to later editions.
 

Related Content

  • Robots, AI and Superb BMW Surfaces

    There isn’t an automotive paint shop in the world that doesn’t have post-paint inspection and defect processing. But BMW is doing this with levels of technology at a plant in Germany that exceed all other paint shops in the world.

  • Curing Oven Basics

    Simply heating up the substrate does not cure the coating. There are many variables to consider when choosing the best cure oven for your application...

  • Henry Ford Is Still Right When It Comes to Color

    Who would have imagined that more than 100 years after his famous statement about any color as long as it’s black would still have relevance of a sort?

Your Best Finish Starts With Us!
Precision gear pumps
ENGINEERED PAINT BOOTHS & FINISHING SOLUTIONS
Gardner Intelligence
The Finishing Industry’s Education and Networking Resource
PF Podcast
plating and surface finishing additives
OptiCenter All-in-One OC11
Industrial Finishing Equipment