To measure by volume or weight? Which is better and why?
To summarise this blog post, weight is the best option to measure materials, but why?
The first thing to do is to understand the difference between volume and weight. Volume is defined as ‘the amount of space that a substance or object occupies, or that is enclosed within a container’. Weight is defined as ‘a body's relative mass or the quantity of matter contained by it, giving rise to a downward force; the heaviness of a person or thing’. For example, 1kg of feathers and 1kg of lead weigh the same, however, due to the nature of the feather's composition, the feathers will take up more space than the lead, meaning it has greater volume.
This means that if you are measuring components with different volumes such as a powder and a liquid, this could be misinterpreted under many variables.
One variable includes whether the powder has been compacted or aerated, which would mean a different mass of powder could be measured in the same measuring cup depending on the constitution of it. In addition to this, if using the prints on the side of a mixing cup to measure, these could be misprinted and vary from cup to cup.
This is essential to consider when working with volatile materials such as silicone, or when working in small quantities. This is because, in a small quantity, any misinterpretation could mean a massive error margin throughout the whole batch which could cause the product to be unusable. Not only is this wasteful but also uneconomical.
On the other hand, when using a reliable set of scales to measure materials, the error margins are slimmer, as we can accurately measure materials regardless of the volume. Scales also help when working in small ratios (such as 1:16) which would be difficult to measure inside a printed mixing cup. I would recommend using a small set of scales (often used for weighing small animals) that reads to 1/100 of a decimal point when working in small quantities. This is how I can accurately measure silicone paint mixes when making small silicone props as well as many other applications.
As pictured, is an example of a misprinted, or otherwise inaccurate cup. My reliable scales read 100g, however, the mixing cup reads just over 110g. This margin of error could be potentially defective, showing you how important it is to measure correctly!
Hopefully, this gave you some insight into the technicalities of making prosthetics (or baking cakes) and benefited you in some way!
Keep creating, Poppy.
