Bob's Discount Furniture has been a popular furniture mainstay in the northeastern and midwestern U.S. His Bobopedic brand was made famous by the Bob's television commercials over the 20 years and offers memory foam, hybrid, and latex mattresses. These mattresses have competitive price points for the materials used
The deformation measurement represents an essential part of the investigation. It serves to register the real spherical change of the mattress surface while lying down. Depending on the properties of the mattress, a more or less clear negative shape of the lying body can be shown. The deformation measurement is the end result of many path measurements, which, with the help of sensors on the surface, record the height position of many points on the surface that has changed as a result of use. In all areas where the body is in contact with the mattress, this method is used to reproduce the boundary layer between the body and the body-supporting system during use.
The recording of the surface form by distance measurement is carried out with the subjects lying on their backs and sides. As mentioned above, the 5th female and the 95th male height/weight percentile are included in the study.
For the percentiles examined - and thus for the entire height/weight range - and body postures, it must be checked whether the mattresses provide sufficient support. The emerging body contours must correspond to postures that are within the physiological range. It is determined whether there is a disposition to a kyphotic posture (hunched back) on the one hand and an unphysiological position of the spine in the lumbar area when lying on one side on the other. The body contours must be balanced and the angles of the individual body parts must be in favorable proportions to one another. In addition to the deformation measurements with the previous test person groups, which represent the limit percentiles (P5 ("petite") and P95 ("large/tall")), investigations were carried out with subjects of an average physique type ("average"). The evaluation of the results of the supporting properties is differentiated according to the supine and lateral position.
The stabilization of the body on the mattress (without the need for static muscle work) is a very important quality feature. It is therefore necessary to check to what extent a mattress can be set in rocking movements or vibrations by a sudden shift in the weight of the sleeper. A method is used to test the damping or post-oscillation behavior of the mattress, which simulates the "swinging" lying down or rolling around of a person with the 95th percentile of body weight. A test weight of 17.5 kg (hemisphere shape, 36 cm Ø) with a drop height of 30 cm is used. The vibration caused by this or the vibration damping of the mattress is recorded in terms of its frequency and amplitude of the after-vibrations using a displacement transducer.
pressure distribution measurement
The pressure distribution is measured in the supine position with a subject of the 50th percentile height and body weight in adults. A pressure measuring mat is used for this. The maximum pressure measured is given, whereby the values in the back of the head and heel area are not taken into account.
The point elasticity of the mattress is determined on the basis of the sinking values of the shoulders and buttocks of the 95th percentile: Two dome-shaped test stamps (diameter 165mm) are pressed into the mattress at a distance of 430mm and a feed rate of 90mm/min with the force with which the Maximum sinking depths at the shoulders and buttocks (taken from the deformation measurement) can be achieved. The point elasticity is specified as the difference [mm] between the indentation values of the test stamp and the maximum in the unloaded intermediate area.
Determination of the residual height
The so-called residual height is a measure that characterizes the ability of a mattress to keep a minimum height of suspension material below the load point, even with larger sinking values. This means that even heavy people should not feel any contact with the substructure. This negative effect occurs in particular in the case of mattresses with a low overall height, coupled with a soft firmness setting. Contact area / change of position resistance measurement
The size of the contact area that exists between the lying person and the mattress in standardized postures depends on the type of underlay/upholstery and must be considered from two points of view: With a completely unpadded planar body support, the contact area takes up only about 20% of the projected one body outline. In practical terms, this means that the force exerted by the body on the support is transmitted only in very limited zones, thereby overstressing the soft tissues in these regions. In the case of a very hard mattress, this could mean, for example, that a contact surface in combination with the tendency to vibrate, which is often present in hard upholstery material, causes instability in the posture or produces very high pressure values.
On the other hand, by designing the padding appropriately, it is easily possible to achieve a contact surface that fits the body so completely that it “swims” in it, so to speak. This solution is not desirable either, since such a surface design restricts the required freedom of movement of the person lying down. In addition, under microclimatic aspects, insufficient ventilation and the resulting increased tendency to perspire on the part of the sleeper may have negative effects.
The contact surface between the person and the mattress is shown and measured in the supine position with the legs slightly apart and the arms also slightly stretched out from the body. According to the results available so far, the contact area should cover at least 30%, but preferably a larger proportion of the projected body outline, with the most favorable range being between 46% and 55%. The physiological upper limit of the contact area size is 75%
The determination of the contact area is increasingly being replaced by the determination of a mechanical resistance to change in position (see also 3.8); ultimately a different, standardized and therefore machine-repeatable method for determining the ease with which a person can turn on the mattress into a different position.
Heat development/moisture development
The microclimatic conditions in the bed cavity, in particular the transport of moisture in the mattress, represent another important factor that affects sleeping behavior and the subjectively perceived sleeping comfort. The microclimate on the mattress depends on a number of factors. First and foremost, the material or the material combination of the mattress, the layer arrangement of the outer structure and the shape of the mattress surface should be mentioned. In addition, the deformation properties and the measured contact area also play a role in the microclimate. The larger the contact area, the higher the extent of the transpiration it provokes. In connection with this, effects on movement patterns during sleep can be observed,
Due to their special task of supporting the body during sleep without the possibility of influencing the posture voluntarily, the microclimate requirements of a mattress differ from those of, for example, upholstered furniture, office chairs, etc. With regard to perspiration, it can generally be said that the release of moisture – in the mattress and/or through them - must be large enough during use to avoid a subjectively unpleasant feeling of moisture in the contact surface area, even under unfavorable macroclimatic conditions.
The measurements are carried out in the contact area between the person and the mattress. The values are given in the stabilization phase (between 80 and 120 minutes) at a standardized room climate of 23°C and 50% RH.
shoulder drop effect
One feature that can be noticed, especially in less firm mattresses, is the ventral flexion of the shoulder region. This means that in contrast to a relaxed standing posture, the shoulders are pushed forward and the chest space is narrowed.
Analogous to the measurements in the sagittal plane, this effect can be measured by a deformation measurement in the transverse direction to the mattress in the area of the shoulder girdle, since the present assessment focuses more on the quantitative than the qualitative expression of the effect. A method could be used here that is based on distance measurements between human body to an imaginary frontal plane. The measurement points are the acromia and the manubrium sterni, i.e. bone points that can be easily palpated.
At the beginning of the examination, the distances of the three points are measured while standing in a relaxed "normal posture" to a flat frontal surface. The basis for later calculations are the differences between the distances. Next, the subject lies supine on the mattress in a standardized posture. Again, the distances to the frontal plane are measured and the differences calculated. If the distance between the two acromial measuring points and the one on the sternum decreases, the shoulders are overextended by the mattress. If the distance increases, the so-called shoulder-collapse effect occurs.
displacement resistance
In this study, the force acting in a horizontal direction is measured and evaluated, which is necessary to move the roller described in DIN EN 1957 (5/2000) transversely to the longitudinal axis of the mattress. The vertical force acting on the roller is 1400N. The measured values are documented in the form of a force-displacement diagram. The measurement method described above serves as a simulation for the process of changing the position of a mattress user. In terms of the user, the force to be applied should be as low as possible.
Durability
Test according to norm EN 1957 (roller test)
A long-term load test based on the methodical specifications from the norm EN 1957:2012-1 with 30,000 rolling cycles = 60 thsd compressions is carried out. The methodology of this standard is supplemented by deformation measurements and assessments before and after rolling with 30,000 cycles = 60 thsd. compressions.
Testing under the influence of humidity and temperature (static load)
Furthermore, a static load test is carried out, which takes into account the influence of humidity and temperature on the durability of the mattress. After 100 setting cycles based on the specifications from the norm EN 1957, a defined area of the mattress is loaded with a weight of 1000N over a period of 16 hours. The characteristics of the ambient climate are 37°C with a relative humidity of 80%. A preconditioning of the test objects with these climate data takes place.
After a restitution time of 24 hours in a standard climate (23°C / 50% RH), a force-displacement diagram based on EN 1957 is recorded and evaluated in comparison with that of the new condition.
The evaluation in this summarized form takes into account the type and weight of the mattresses as well as the presence of handles and their suitability. For example, latex mattresses can be problematic from a handling perspective due to their heavy weight and the strong mechanical flexibility of the mattress body. On the other hand, handling of lightweight, thin polyurethane foam mattresses, even if they do not have handles, may not be critical even for persons with low body strength. The type of design of any handles can vary greatly and is therefore part of the evaluation.
Product info
In the case of mattresses, with their generally high proportion of textile fabrics, compliance with the requirements of the Textile Labeling Act is mandatory. In addition, removable mattress covers should bear a care or washing note. Information on the materials used in the mattress core, the construction principle and the resulting usage properties, such as the suitability of the mattress for adjustable substructures, should be viewed positively. Information on the effects of the construction principle and use of materials on the microclimate in the bed cavity is useful and desirable.
In the case of mattresses that are asymmetrically constructed in terms of their zoning in the direction of the head and foot end, this should be declared in a way that is recognizable to the user. The same applies to products with two different lying sides.
Prohibited are so-called inadmissible healing promises that suggest to the user a therapeutic effect that cannot be proven. But misleading statements about product properties must also be avoided. This also includes statements about the absence of toxic or health-endangering ingredients, the absence of which is a matter of course.
Mattress Cover
Processing / packaging
The processing test item includes the assessment of the mattresses as a whole, as well as that of the handles separately. The processing quality is evaluated without taking into account the effort involved in the manufacture and finishing. The sole decisive factor for a good rating is a skilled, professional execution of the work on the mattress. This includes, for example, the clean fitting of zips or the professional locking of seams. In addition to the aspect of processing quality, the type of packaging is recorded and evaluated. This term refers to the constructive effort of the mattress concept and the quality of the processed materials. For example, zoned mattress cores or the use of pocket spring cores are a feature of more complex packaging. In addition to these core design features, properties that characterize the external appearance also determine the value. These include, for example, mattresses whose borders are edged with tucks. washing the cover
For test samples with a removable washable cover, this is washed and dried according to the manufacturer's care instructions. Dimensional stability, color retention and reuse are checked and assessed.
Wetting test
In the wetting test, a defined amount of water is pipetted onto the surface of the mattress cover. After the liquid has dried completely, any stains or edges on the surface of the mattress cover are assessed and evaluated.
Health/Environment
Human Ecological Conformity
Textile fabrics must meet legal and self-imposed standards, which ultimately guarantee human-ecological harmlessness on the basis of a test for harmful substances. This is done by determining the existence and the up-to-dateness and correctness of the following scope of tests:
Climate neutrality: certified CO2 balance of the product over the entire life cycle, compensation of the unavoided CO2 volumes
• Textile technological and chemical tests: e.g. B. Fiber composition, fastness, strength, performance properties, tests for harmful substances in accordance with legal requirements, industry standards and OEKO-TEX
• STANDARD 100 by OEKO-TEX: Testing and certification system for textile raw, intermediate and end products Thermophysiological tests regarding the climate comfort of mattresses
1 Preparation of the samples for the skin model measurements
2 Water vapor resistance DIN EN ISO 11092 - sample thickness more than 3 mm
3 Short-term water vapor absorbency measurement in connection with water vapor resistance
4 water vapor release drying adult mattresses
sustainability
Protection and solutions for future generations are evaluated in stages and checked for the existence and up-to-dateness of the following scopes:
• DETOX TO ZERO by OEKO-TEX: Implementation of the goals as part of the Greenpeace Detox campaign; Existence and topicality check according to OEKO-TEX Appendix 6.
• STeP by OEKO-TEX: Examination of the existence and up-to-dateness of company chemical management, optimization of company environmental performance and environmental management, as well as auditing and certification of social working conditions and safety at work
• MADE IN GREEN by OEKO-TEX: Check that the label is available and up-to-date for items that have been tested for harmful substances and are manufactured in a socially responsible and environmentally friendly manner
Climate neutrality: certified CO2 balance of the product over the entire life cycle by qualified institutions, compensation of the unavoided CO2 volumes in resilient projects (e.g. goldstandard.org), proof of the final decommissioning of the certificates
Price-performance-ratio
The price-performance-ratio adds into the consideration, how much value you get for your money. If the button is activated, each full $500 above $2000 dollars will deduct 2 points (capped at -6) from the total score, each full $500 Dollar below $2000 will add 2 points (capped at +4) to the total score.
Stabilization
comfort properties
stabilization
The stabilization of the body on the mattress (without the need for static muscle work) is a very important quality feature. It is therefore necessary to check to what extent a mattress can be set in rocking movements or vibrations by a sudden shift in the weight of the sleeper. A method is used to test the damping or post-oscillation behavior of the mattress, which simulates the "swinging" lying down or rolling around of a person with the 95th percentile of body weight. A test weight of 17.5 kg (hemisphere shape, 36 cm Ø) with a drop height of 30 cm is used. The vibration caused by this or the vibration damping of the mattress is recorded in terms of its frequency and amplitude of the after-vibrations using a displacement transducer.
pressure distribution measurement
The pressure distribution is measured in the supine position with a subject of the 50th percentile height and body weight in adults. A pressure measuring mat is used for this. The maximum pressure measured is given, whereby the values in the back of the head and heel area are not taken into account.
point elasticity
The point elasticity of the mattress is determined on the basis of the sinking values of the shoulders and buttocks of the 95th percentile: Two dome-shaped test stamps (diameter 165mm) are pressed into the mattress at a distance of 430mm and a feed rate of 90mm/min with the force with which the Maximum sinking depths at the shoulders and buttocks (taken from the deformation measurement) can be achieved. The point elasticity is specified as the difference [mm] between the indentation values of the test stamp and the maximum in the unloaded intermediate area.
Determination of the residual height
The so-called residual height is a measure that characterizes the ability of a mattress to keep a minimum height of suspension material below the load point, even with larger sinking values. This means that even heavy people should not feel any contact with the substructure. This negative effect occurs in particular in the case of mattresses with a low overall height, coupled with a soft firmness setting. Contact area / change of position resistance measurement
The size of the contact area that exists between the lying person and the mattress in standardized postures depends on the type of underlay/upholstery and must be considered from two points of view: With a completely unpadded planar body support, the contact area takes up only about 20% of the projected one body outline. In practical terms, this means that the force exerted by the body on the support is transmitted only in very limited zones, thereby overstressing the soft tissues in these regions. In the case of a very hard mattress, this could mean, for example, that a contact surface in combination with the tendency to vibrate, which is often present in hard upholstery material, causes instability in the posture or produces very high pressure values.
On the other hand, by designing the padding appropriately, it is easily possible to achieve a contact surface that fits the body so completely that it “swims” in it, so to speak. This solution is not desirable either, since such a surface design restricts the required freedom of movement of the person lying down. In addition, under microclimatic aspects, insufficient ventilation and the resulting increased tendency to perspire on the part of the sleeper may have negative effects.
The contact surface between the person and the mattress is shown and measured in the supine position with the legs slightly apart and the arms also slightly stretched out from the body. According to the results available so far, the contact area should cover at least 30%, but preferably a larger proportion of the projected body outline, with the most favorable range being between 46% and 55%. The physiological upper limit of the contact area size is 75%
The determination of the contact area is increasingly being replaced by the determination of a mechanical resistance to change in position (see also 3.8); ultimately a different, standardized and therefore machine-repeatable method for determining the ease with which a person can turn on the mattress into a different position.
Heat development/moisture development
The microclimatic conditions in the bed cavity, in particular the transport of moisture in the mattress, represent another important factor that affects sleeping behavior and the subjectively perceived sleeping comfort. The microclimate on the mattress depends on a number of factors. First and foremost, the material or the material combination of the mattress, the layer arrangement of the outer structure and the shape of the mattress surface should be mentioned. In addition, the deformation properties and the measured contact area also play a role in the microclimate. The larger the contact area, the higher the extent of the transpiration it provokes. In connection with this, effects on movement patterns during sleep can be observed,
Due to their special task of supporting the body during sleep without the possibility of influencing the posture voluntarily, the microclimate requirements of a mattress differ from those of, for example, upholstered furniture, office chairs, etc. With regard to perspiration, it can generally be said that the release of moisture – in the mattress and/or through them - must be large enough during use to avoid a subjectively unpleasant feeling of moisture in the contact surface area, even under unfavorable macroclimatic conditions.
The measurements are carried out in the contact area between the person and the mattress. The values are given in the stabilization phase (between 80 and 120 minutes) at a standardized room climate of 23°C and 50% RH.
shoulder drop effect
One feature that can be noticed, especially in less firm mattresses, is the ventral flexion of the shoulder region. This means that in contrast to a relaxed standing posture, the shoulders are pushed forward and the chest space is narrowed.
Analogous to the measurements in the sagittal plane, this effect can be measured by a deformation measurement in the transverse direction to the mattress in the area of the shoulder girdle, since the present assessment focuses more on the quantitative than the qualitative expression of the effect. A method could be used here that is based on distance measurements between human body to an imaginary frontal plane. The measurement points are the acromia and the manubrium sterni, i.e. bone points that can be easily palpated.
At the beginning of the examination, the distances of the three points are measured while standing in a relaxed "normal posture" to a flat frontal surface. The basis for later calculations are the differences between the distances. Next, the subject lies supine on the mattress in a standardized posture. Again, the distances to the frontal plane are measured and the differences calculated. If the distance between the two acromial measuring points and the one on the sternum decreases, the shoulders are overextended by the mattress. If the distance increases, the so-called shoulder-collapse effect occurs.
displacement resistance
In this study, the force acting in a horizontal direction is measured and evaluated, which is necessary to move the roller described in DIN EN 1957 (5/2000) transversely to the longitudinal axis of the mattress. The vertical force acting on the roller is 1400N. The measured values are documented in the form of a force-displacement diagram. The measurement method described above serves as a simulation for the process of changing the position of a mattress user. In terms of the user, the force to be applied should be as low as possible.
