Appendix 10
Shower Heads: What Sprays and Handles to Choose?
A10.1. Excerpts from recommendations for selecting the type of spray
The spray jets that are provided in various models of shower heads, which need to have a satisfactory level of power, come in a very broad range, according to:
- – the continuous or pulsating nature of each elementary jet;
- – the basic number of jets produced the stream (a more or less abundant spray or a single jet);
- – the size and configuration of the stream of the jets when leaving the spray nozzle (splash, crown, focused or mixed stream);
- – the shape projected by the stream of jets (parallel, divergent (conical) and convergent (focused at a distance) jets);
- – the size and physical appearance of each basic jet (fine and tight, medium-abundant, medium-vigorous, medium-foam, thick foam).
The indications generally given in catalogs, on the Internet or on packaging, labels such as “rain jets” are not sufficient to fully characterize the type of jet that produces the model of spray considered. “Rain jets” always consist of continuous streams which are relatively homogeneous and mostly fine and tight.
However, the stream provided by these kinds of jets while leaving the spray nozzle is either a rather large flow or shaped in a ring of a rather large diameter; and the projected jets form a parallel stream, or basically diverge (into a mostly open cone). For a handheld shower head, the efficiency and aptness of the spray for cleaning (initial wetting, rinsing, sprinkling, spray for well-being) mostly depend on these latter characteristics.
To be more useful, rain jets should provide a stream:
- – with many jets that are very thin and regular, for the effect of “energetic softness”, without deviating jets that are too strong or that drip – the jets should be moderately large (about 70 mm), for more precision when spraying limbs, the head or recesses of the body;
- – quasi-cylindrical or very slightly conical when the shower head is handheld and operating naturally, by spraying in a wreath rather than a ring, for a comfortable feeling and a more uniform effect on the skin, without having to operate back and forth movements that are too fast (the effect of a crown stream causes a slight tickling sensation for some);
- – made up of continuous streams that are tight and very distinct, preserved by the action of sweeping motions without sluggishness or a stinging effect, or too much splashing across the skin.
These are practically the selection criteria for a primarily handheld shower head which offers rain jets, like almost all shower heads.
The types of jet stream can be reduced to continuous streams or pulsing streams, the latter of which are often feared by young children because of their overly stinging effects, and are in all cases the origin of excessive spraying by bouncing off the surrounding walls.
In such a case, the shower space must be fitted with protection devices in order to be effective (shower curtains, a shower stall, etc. and it must be the right height and sufficiently “sealed off”).
The unique, foaming, fluffy and soft jet meets special requirements, such as the final rinsing of a baby, the washing of one’s head above a bathtub or even a sink, or the washing of well-defined areas adjacent to a wound that has to be kept dry.
To provide a sufficiently efficient and pleasant feeling, this unique jet is akin to that of a spout with a spray nozzle (of a “neoperl” type), which must be very dense, with no soft dripping in which the foamy texture is not produced.
Although abundant, this type of jet has very little risk of splashing when the shower is handheld and sprayed in close proximity or splashed.
The continuous-type jets with a reduced and concentrated stream, with a few foamy and abundant jets, are a compromise between a small stream in a sheaf of parallel jets with medium abundance, and the type of jets just described.
This former type of jet, with an abundant supply, is of interest for bathing that is already effective for young children, sore or deficient body tissues (such as venous disorders) and the faces of people who fear that the rain jets are too lively.
However, the speed of the rinsing, or its effectiveness if the duration is insufficient, is less favorable than with the rain jets previously described.
The low risk of splashing makes it a nice type of jet for unwilling approval, or for children’s games that are played under the shower.
As for the mixed types of jets, they are usually the least popular, because of their initial lack of a defined form (neither one nor the other type of jet) and their cumulative disadvantages, often feared by the users of one or the other of the types of jets considered.
This tendency is found to be frequently confirmed by the deliberate choices of one or the other when the user is using a spray that allows them to pass gradually from one type of jet to another.
A10.2. What comfort and security of grip should be chosen in a handheld shower head?
A10.2.1. For a satisfactory grip
The feeling of a comfortable and secure grip on the handle of a spray nozzle of a given model will vary, of course, based on the measurements of the user’s hand.
However, this feeling is very different when gripping with hands that are just wet, and gripping with hands that are also soapy. Although the performance differs little between a grip with dry hands and grip with wet (but not soapy) hands, the slightest trace of soap on one’s hand is “unforgiving”. This is an excellent criterion for deeming a grip to be satisfactory.
We must be careful: this grip cannot be evaluated with just the showerhead, when it is disconnected and without the hose. It is not just a case of holding the shower head in one’s hand like a statue, but of moving it around, pointing it in the specific directions, controlling the hose in the same motion and dealing with the side effects that it generates.
The more the user has to squeeze the handle of the nozzle to move it around, the more critical the grip can become if its characteristics are unfavorable.
To be able to suit the many different sizes of hands, the following changes can be recommended: a handle section in the range of 5–6 cm2 that is circular in shape (diameter of 2.5 to 2.8 cm) or similar; not “falsely flat” that is large in size or with an angular and more or less rounded part, which would hamper the rotation of the handle inside the hand for all purposes.
Square, rectangular or polygonal cross-sections do not allow for a better grip with soapy hands.
Increased discomfort also increases the tendency to tighten more, and the hand–handle adhesion is not any better.
Thus, the following should be avoided: forms that are slightly conical or pyramidal (a large section on one side or the other); prismatic shapes with varying sections along the length of the handle; and handle forms that have substantial curved segments, even with a uniform cross-section.
It is also necessary to be wary of elements with additional forms, which can include, for example, a wave-like form in the lower area, intended to convey a pseudo-ergonomic image of a handle that would be easily held in the hand. It is as if the users were holding a shower head like a tool, with their fingers clamped down in the best possible place; and as if every user spaced their fingers the same way for gripping objects.
Certainly, it is not useless to emphasize that the different areas on the shower head to grip (handle, head or crown, if one is used) should be free of bumps or bulges that stick out, or protruding ridges on the connections between component parts.
The position of the hand on the handle depends on the effort needed to keep a firm grip on it. The hand naturally tends to position itself in such a way as to find the best balance of masses that are cantilevered and in movement.
Even when full of water, the head of the shower nozzle, sometimes “alleviated” by the effect of the reaction of some jet settings and a high pressure, rarely acts as a counterbalance to the variable weight of the hose, which is usually moving. Sometimes, the torque necessary to correct the radial position of the spray relative to the hose may be added (the lack of initial positioning, the tightening of the seal of the hose).
In use, an outdoor shower is often held with the hand very far down on the grip, with the hand spilling over onto the conical fastener on the hose, in order to reduce the effort required.
A shower should also have a grip that is much longer and lighter, that is, a minimum of about 12 cm (for very wide hands) centered around the typical static balance point on the hand.
A10.2.2. For satisfactory wrist movements
Users unconsciously try to orient shower jets in order to obtain a spray that is as efficient as possible, or at least what they perceive as being so.
At the beginning, there is a sufficient degree of moisture on skin that has been sprayed and a uniform wetting of all surfaces that are desired to be used. During rinsing, this involves as complete a removal of the cleaning or treatment agents as possible, as well as some of the impurities that are involved, which serve to guide the continuation or not of the spray.
Some adverse effects from the jets are also to be prevented in certain cases.
The angle of the stream of the jets relative to the direction of the handle, and more specifically, the effective area of the grip on the handle, plays a very significant role in determining the movement of the rotation of the wrist, as well as the efforts that the wrist must develop to maintain the jets in the desired direction.
If making a simple sweeping movement does not present particular difficulties in using the elbow joint in large part, this is not the case when the hand must rotate around the wrist, more or less curved outward, or bent towards the inside, up to extreme levels (the levels are sometimes limited, particularly by age or certain joint conditions).
For spraying body parts on the front of the body, holding the shower head straight or at a very slightly acute angle is best.
For spraying most of the surfaces that are oriented to the opposite of the arm that holds the shower head, such as the back, the skull or the perineal area, an acute or very acute angle helps to limit the bending of the wrist towards the inside (orienting the head at an obtuse angle or with no angle is not recommended).
For spraying most of the surfaces facing the side of the arm that holds the shower head, such as to the underside of the opposite arm, an obtuse angle or no angle allows the curvature of the wrist to the outside to be limited, and reduces the discomfort from a hose that becomes essentially “stuck” between the hand and the rest of the body (shower heads at an acute angle and, above all, a very acute angle are not recommended).
These last two requirements are contradictory for showering with the shower head held in one’s hand, especially without having to constantly change hands for increased comfort of the wrists; a compromise value for the angle would be somewhere between a 75° and 80° angle (slightly acute).
A10.3. Usage analyses made by Michel Jullien, usagist designer; Dominique Royer, designer; Michel Millot, project manager
Until recently, the essential knowledge on the subject of use virtually did not exist, at least in written form. The conscientious practice of the many analyses of use has been a valuable resource and the fundamental basis on which this book has been written. This “scientific” material acquired by the team, thanks to the sixty studies listed in the book Guide du design industriel (Millot 2017, p. 222), needs to be distributed, operated and maintained by a system for the information on products to be used by consumers and designers. This knowledge has a high level of added value, because it requires original and very human analysis.