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Advice on Stainless Steel Sinks
These days, most stainless steel sinks are manufactured using a process called deep draw forming where a sheet of metal is drawn down into a form through a series of steps called reductions. This is achieved using a large press where the sheet metal is pushed by a negative of the sink from underneath the sheet. Each reduction stretches the sheet metal deeper and deeper into the form, so what started out as one thickness of sheet of metal will not end up being the same thickness throughout the entire finished product. The industry standard is to state the gauge of the metal that the manufacturing process started with. Since this is the standard practice, it makes it easy to compare one sink to another. Upmarket manufacturers usually follow tighter tolerances in the finished gauge of the product. The process causes the metal to become brittle so it softened and toughened using a process called annealing.
Why does this matter ? In an nutshell quality.
Due to the difficulty in forming stainless steel sinks, many manufacturers have built up an accumulated experience in the process. The sharper the inner corners of the sink and the deeper it is, the more skill and time it takes to manufacture.
Take a look at this budget sink. The first thing we notice is that it is very shallow. If we look further you can see the internal side corners are very rounded. More of a problem is that the bottom of the sink has very rounded corners and the sides are slightly inclined. So if your sink opening measures say 380 mm front to back, it may be little more than 250 mm at the bottom. There are some of these sinks where a large plate will jam between the sides before it reaches the bottom of the sink.
The difference doesn't end there. If you could turn the sink upside down you will see that the budged sink is punched out of one piece of sheet metal, this causes stress to the sink and an uneven thickness of metal. To aid the manufacturing process, on a budget sink you often see a lower grade of stainless steel used and a thinner gauge of metal. That said, they can sometimes be found at an exceptionally low price and are functional enough if you are on a very tight budget.
To achieve the superior qualities in the second sink, the bowl is manufactured separately from the drainer, welded to it and finished to look seamless. Of course there is a cost premium to pay but worth the extra if you are fitting a quality kitchen or spend a lot of time at the sink.
Best Stainless Steel Sink Gauge. 16, 18, 22 ?
Stainless steel sinks are manufactured using different thicknesses, or gauges of sheet metal. The lower the number the thicker the metal. The most common gauges used are 16 and 18. The thinner 22 gauge is sometimes found on budget sinks or as components on a complex fabricated sink. (see below) . For some designs, 18 gauge may be used as it is easier to form into tighter shapes and 16 gauge may be more suitable for large sinks where a fractional increase in stability is welcomed. As a general rule both 16 gauge and 18 gauge are suitable for most sinks and although on paper 18 gauge is is stiffer and more resistant to dents, the difference is minimal but it is often used as a marketing tool to sell more upmarket sinks.
The grade of stainless steel used in manufacture is perhaps more important than the gauge of the steel. The three most common grades available in stainless steel sheet metal are: 304, 316 and 410. Grade 304 is a quality steel where the carbon and the iron is well bonded and called austenite stainless steel. It is made up of at least 8% nickel and up to 10%. It is the most frequently used of the three grades of metal. A good sink is made from 18/10 stainless steel.
18 / 10 refers to the chromium (18%) nickel (10%) content in the steel which gives it the high level of stain, corrosion and rust resistance we associate with the material.
A simple test to check the quality of the stainless steel is with a magnet. If a magnet sticks to it then it is poor quality. If it does not, it may not be the best steel you can buy but it is still a quality steel.
What about the grade of the stainless steel ?
Advantages of a stainless steel sink
Surface is easy to clean and hygienic
Does not alter flavour of food.
Requires very little upkeep
Fabricated Stainless Steel Sinks
Sinks manufactured by fabricating sheet steel are becoming ever popular. Using this method, sheet stainless steel is cut to size and a large press called a press brake forms the wall and base of the sink by folding the steel. The seam is then welded together and finished so it looks seamless.
The advantage of this method is that as the sheets can be folded tight therefore the corners of the sink are a lot sharper and can have a near zero radius internal corners. As well as being very practical in terms of space as they give a cleaner line. Cleaner, finer lines are very much the style of the moment.
Surface finish of stainless steel sinks
During the manufacturing process the steel will get scratched and marked, to ensure the sink has an attractive finish the surface of the steel is treated in a number ways, The most common surface finishes of stainless steel sinks are polished, satin or Matt. A satin or matt finish is usually achieved by brushing the steel but can also be achieved chemically by etching.
Polished surfaces can look very attractive when new but unfortunately stainless steel scratches very easily and your new polished sink may not remain polished for long. This accounts for the majority of stainless sinks being supplied in a brushed or matt finish.
There are also many other finishes which can be applied to the steel for example an embossed to emulate a pattern on the surface or a linen finish whereby the steel is finished in opposing lines or patterns to simulate a fabric look. Blackened, bronzed and coppered are where the steel is chemically treated to match the corresponding colour finish, or even a hammered finish where the sink is left looking hand beaten.
Traditional, brushed satin finish.
An example of an embossed linen finish.
An unusual blackened "anthracite" finished sink by Alveus.
Alveus offer a number of unusual finishes including their "gold" range
A "modified" hammered look finish to the stainless steel.
A selection of stainless steel sink finishes.
Click the images to see a larger image.
Noise suppression and insulation of stainless steel sinks.
One disadvatage of stainless steel sinks is their ability to resonate and amplify the noise of running taps and the clatter of dishes and utensils. To combat this most stainless steel sinks are fitted on the underside with one or more insulation pads to deaden the noise, such as the large, black pad fitted to this sink.
In these days of energy efficiency awareness, many sink manufacturers are starting to take the problem of heat insulation more seriously and coating the inderside of their sinks with a heat insulating layer.
This in theory should help keep your dish water hotter for longer and deaden the sound more. There is an added bonus of reducing the risk of condensation to the underside of the sink. Although not a common occurrence, this can happen when the sink is filled with cold water and the surrounding air is warm and moist, a not uncommon air condition in kitchens.
Compare with this quality manufactured sink. It is deeper, the corners are much tighter and the bowl is as near to the same dimensions at the top as it is at the bottom.
The nature of stainless steel is that it is very difficult to form into a shape without the metal tearing. At one time this was mainly achieved by spinning the sheet of metal in an offset pattern and a small roller or ball was pushed at high pressure to effectively continuously bend the metal into shape.
Fabricated, stainless, full and half bowl sinks.
A butler sink fabricated in stainless steel.
A stainless steel worktop welded to a stainless steel sink to create a seamless workspace.
Some manufacturers can produce a stainless steel work surface incorporating a seamless, integrated, stainless steel sink. Shown is an example from the "Steelart" range from Blanco.
Disadvantages of a stainless steel sink
Some find the look of stainless steel a bit too industrial and uninspiring.
It is highly susceptible to corrosion from strong acids and alkalines.
It is easily scratched.
It can resonate causing sounds to become amplified.
Stainless steel conducts heat well thereby cooling your dishwater.