I've noticed a trend recently that some sinks have a flat base, but they seem to be few and far between. Are there any reasons related to UX for why sinks have traditionally always been round?
Commercial sinks are "flat" by industrial design. There is a specific sequence for hand cleaning dishes that specifies three compartments for washing, rinsing and sanitizing.
They are designed to be filled with water. They are flat to hold the maximum volume of water and items to be washed. It's all based on a tried and true design tested in countless restaurant kitchens.
Residential use sink design is driven by style but favors roundness for a few reasons that I can merely speculate on.
They originate from washing bowls and they likely continue the legacy of that design.
The utility of a rounded design is favorable in residential use because it's easier to clean and it splashes much less when water is running in an empty sink. A flat is better if the sink is deep and I notice that the deepr a sink design, the flatter it is.
At my (tech not food service) job, the kitchen sink is a shallow flat design and it sprays everywhere when the water is turned on. Everybody avoids it.
Most domestic sinks (but not all) are rounded because:
- They are cheaper to make, as you can simply press them out of a flat piece of steel. You can't press out corners easily like this as they will tear in the pressing process.
- They are easier to clean with a sponge or cloth. The same applies to dog bowls by the way, which is why squared dog bowls are very rare.
- They are stronger due to their geometry.
- People are used to them.
Comercial sinks are often squared, as well as domestic sinks that have special purposes. My home sink is squared for example, so that it fits my oven trays perfectly.
Flat sinks are common in industrial settings. They're usually filled completely and so having something that holds the largest volume and where things stack easily and you have a stable surface.
For the home you tend to get rounded sinks. As @Itumac mentioned it's at least partially from historical reasons. But there are utilitarian ones too.
Flat sinks tend to splash when filled - rounded do not
Flat sinks take more effort to clean and maintain since they drain less effectively and have "corners".
Flat sinks take much more water to be useful. With a rounded sink you can fill the bottom of the bowl rapidly to a useful depth for handwashing or cleaning.
Rounded sinks hold less water - which is useful in residential settings when less water is normally needed.
I'd say the rise of flat sinks in the home is more a fashion issue of people liking a more industrial look to their kitchens and bathrooms.
The trend must be based on style rather than function. Here is a commentary on flat sinks in the home.
In kitchens, flat sinks have always been around.
A flat sink provides a better work surface for washing dishes, food, utensils.
Stainless steel sinks are also more popular in kitchens because the material is more resilient than other comparably priced materials. Also, making a flat bottom steel sink is easier than a rounded steel sink.
If the bottom is flat you have to mount it perfectly horizontal or the high end won't drain properly. With a rounded profile there's more margin for error.