For Density Measurement, Precision is Key Reply

Density is a measure of the mass to volume or weight to volume ratio of a material. This is an important property for systems that relate weight to volume for mixing or dispensing purposes. Volume measurements using traditional methods such as measuring cups or spoons, or even measuring pipettes, are imprecise. Knowing the density of a liquid or coating allows us to instead measure out precise volumes by weight or mass using a high resolution scale. In order to do this, the density of the material must be known. The question is, how can we precisely measure the volume of a material in order to calculate its density in the first place? The answer is density cups.

Density cups are manufactured to a very precise volume. By filling this container to that precise volume and then weighing it, we can calculate the density of any liquid. One of the major problems with filling a container to a precise volume is the meniscus. Liquids tend to be cohesive, meaning the individual molecules attract each other. This is why when we fill a container to the very, very top, we can often see a small mound of liquid that extends above the rim of the container. This is called the meniscus:

meniscus on a glass of water
meniscus on a glass of water

The meniscus means that the volume of the liquid in the container is actually slightly larger than the volume of the container itself. To solve this, density cups have a precisely fitted lid with a small hole in the center and a rim that extends slightly into the cup. The cup is filled with more liquid than is needed, and when the lid is placed on top the excess material will flow out of the hole. Wipe away the excess and voila – the cup is filled precisely with the appropriate amount of liquid.

image to show removing of meniscus

The liquid is then weighed in grams, which can be achieved either by zeroing the scale before filling the cup or by using a tare weight, which ensures that only the mass of the liquid is measured. One thing to note is that bubbles in the liquid can throw off a density measurement. If a material must be shaken or mixed vigorously, which can cause bubbles in the liquid, it is often a good idea to do the mixing well in advance of the density measurement so the bubbles have time to settle out.

Once the mass in grams is known it’s a simple calculation to arrive at the density. For US density cups, which have a volume of 83.2 ml, simply divide the mass of the liquid in grams by 10 to achieve the density in pounds per gallon (lbs/gal). US Midget Cups have one tenth the volume (8.32 ml); with these cups the mass of the liquid in grams is exactly equal to the density in lbs/gal, and they also have the benefit of requiring less material for measurement. For imperial or ISO density cups which have a volume of either 50 or 100 ml, simply divide the mass of the liquid in grams by the volume of the cup to achieve the density in grams per ml (g/ml, or g/cm^3). Once the density of the liquid is known, any desired volume can easily be converted to a mass or weight and measured out with a scale.

Density and Specific Gravity table
Table courtesy of BYK-Gardner

A Shocking New Innovation in Coatings – See How Conductive Paint Could Change the Future Reply

For those that don’t work in the paint industry, they may think that paint is paint and there’s nothing much exciting going on there. In fact, quite the opposite is true. We’ve written about color changing paint and advances in graffiti-resistant coatings. Developing paint is essentially a chemistry project, but the advancement we’re going to discuss today came not from the mind of scientists, but a group of design creatives that engineered an exciting new paint that could change commercial and industrial painting – conductive paint.


Advances in Paint Chemistry: Amazing Solutions for Increased Aerodynamics Reply

It seems so obvious in hindsight: reducing the drag on an airplane, boat, or car would increase fuel efficiency and provide cost savings for the operator of the vehicle. Until now, that solution was best managed by trying to implement a smooth top coat as any imperfections, dents, or layering in the paint would increase drag. Even a microscopic imperfection would, over time, result in hundreds or even thousands of dollars in wasted fuel cost and increments of wasted time as a transport vehicle inefficiently arrived at its point of destination.


Enhanced Service: Offer Commercial and Industrial Fire Protection with Intumescent Coating Reply

Fire protection is a concern for both your residential and commercial clients, but in certain types of commercial facilities, fire is a much greater risk and one that you can help address with specialized coatings as part of a paint project. Of course every business should have smoke detectors, sprinklers, fire alarms and extinguishers, but beyond this, many of your clients may be surprised to know they can get additional protection from fire risk in their choice of paint products.


Glass Coating Chemistry and the Painting the U.S. Space Shuttle Reply

As you might imagine, much of the construction, design, and deployment of NASA’s space shuttle is unique and without precedent. Each implementation of technology in the space program is, quite often, the first time such an implementation has occurred. NASA’s cutting edge research and development also gives scientists a chance to try bold new things in bold new ways. One challenge NASA scientists must address for every object sent into space is how to handle the massive temperature fluctuations between outer-space and the earth’s atmosphere. Just as significant is the substantial heat and surface friction that spacecraft encounter as they re-enter the earth’s atmosphere and temperatures reach nearly 3,000 degrees Fahrenheit. Protecting astronauts, cargo, and the spacecraft themselves is a core objective within NASA’s ranks.


A Quick & Cost-Effective Alternative: Practical Differences Between Staining & Painting Reply

My wife and I chose a concrete patio for the backyard instead of a wood deck. I figured that the wood would need replacing sooner than the concrete and with plans to have children one day, a place where they could ride bikes and draw chalk art seemed like the right decision. The contractor we chose worked all day to finish the job. They prepped the site, framed the patio, added fill-dirt, and poured the concrete. Long after the sun set, JR was smoothing out the concrete while one colleague held a flashlight and the other gathered up the mess from the day. JR’s team prodded amazing service from start to finish and the resulting concrete patio looks great to this day.

As JR was leaving that night, I asked if he had any suggestions as to how I should paint the patio. I told him we wanted a color that fit well with the brick and stone on the house. He quickly said, “Have you considered staining the patio? It won’t cost as much and the texture and tone of the concrete should come through. I think that would look a lot better than covering it with paint.” I took his advice and a week later I stained our new patio, and JR was right – it looked great. More…

Right of Way: Traffic Paint Chemistry, Manufacturing, and Application Reply

The traffic jam seemed unending. Kate and Ed were traveling home from an early dinner and the road leading to their home was so congested with other cars that they barely seemed to move at all. Eventually, Kate spotted the problem up ahead – the left lane was closed for roadwork, meaning all cars had to shift into one lane. When the pair finally passed the delay, Ed observed that the workers were repainting the yellow and white lines on the road. “That’s great…” Ed said in a sarcastic tone. “There was nothing wrong with the old lines. Why couldn’t they paint the new lines in the middle of the night when fewer people are using the road?”


Try Soundproof Paint for a Simple, Cost-Effective Alternative to Insulation Reply

Kathy had to admit it: her son’s rock band was getting better. What started as a cacophony of electric guitars and kick drums now sounded like actual music whenever they played. The band was scheduled to play a high school talent show in just a few weeks, so the game room of her home had been turned into a rehearsal space. Kathy was very proud of the progress they had made, but at the same time she was hopeful that once the show was over, things would go back to normal and the house would go back to being quiet and peaceful. Yes, the band was getting better – but they were still so LOUD.


How Does Paint Dry? The Practical Implications of Paint Wicking for Professional Painters Reply

Luis had been out sick for three days when he finally returned to finish the job. The client was glad that Luis was feeling better and eager to see the job finished. All that remained was touching up the wall near the trim. Luis had a steady hand and was sure the client would be excited with the final result.

However, after finishing all the corner-work and trim work, Luis started to notice that the paint appeared to be a different color than the rest of the wall. The difference was subtle and it was unlikely anyone, including the client, would ever notice. But Luis noticed, and it aggravated him. As he lay in bed ill for the previous three days, he had worried that this might happen. Some of the paint he applied today was actually going over the paint from earlier that had already dried. And that was causing a problem.


To Catch a Crook: The Spectrophotometer in the Crime Lab Reply

If you’ve ever seen an episode of “Law and Order” or “CSI,” then you likely possess a basic understanding about how forensic science plays a role in helping solve a crime. From fingerprints to mud stuck in tire treads, evidence of all types can help investigators figure out what happened and who is responsible.

Would you believe that one of the tools used by forensic scientists to solve crimes is actually a tool commonly used by professional painters? It’s true: you may think that a spectrophotometer exists simply to help match colors at the paint store or confirm color at a paint manufacturing facility, but in reality, spectrophotometers have a wide range of uses, including in the crime lab as forensic scientists work to understand what happened in a criminal event.