Answer. A table is well engineered if it does its job simply and efficiently without developing any problems. One of the most common problems with portable massage tables is that they are rickety or squeak.

When people talk about strength, they are usually referring to the weight the table will support. Most portable tables will support a static load far in excess of the levels they are subjected to in normal use. Equally important is how rigid the table is when it is pushed longitudinally or laterally, and how rigid it will be a year or so from the purchase date. Flex is also an important consideration in some modalities, e.g. chiropractic. Tables with centre legs tend to be more rigid and show less flex than tables without centre legs.

Some of the other factors affecting the engineering quality of a table are listed below.

[Q11.3] Frame. Frames can be made from aluminium, timber or steel, with aluminium being the lightest, and steel the heaviest. If the frame is made from timber it should use a lightweight hardwood such as Pacific maple; not softwood such as pine that is not as strong, and often comes with knots, which further reduces its strength. Timber frames should be both glued and fastened to the plinth so they can never work loose and squeak. Avoid frames that are attached solely with a nail gun for cheapness and convenience. Metal frames should be rivetted or bolted to the plinth, and if made of steel it should be treated or powder-coated to reduce future problems with rust. Aluminium framed tables never suffer from rust problems.

[Q11.4] Plinth. Plywood is generally regarded as the best material for plinths on portable tables because of its strength and light weight. However there are many different types of ply, ranging from cheap and nasty, to very high quality marine grade. The thickness of the ply also impacts its suitability. The type that is used depends to a large extent on the type of frame and the method of fastening the ply to it. The lightest tables use an aluminium frame with a very thin, high quality ply plinth rivetted to the frame. The ply is stretched like a drum skin and relies more on the way it is fastened to the frame than on the thickness or inherent strength of the ply. Timber framed tables rely more on the strength of the ply, and the better quality tables use at least 9.0 mm thick ply. Lesser quality tables use 4.0-7.0 mm. The highest quality timber framed tables use structural grade ply that has been tested to A.S.A. standards. A plinth that has been properly glued on to a timber frame is permanently attached, and can never come loose or squeak.

Steel-framed tables can use a variety of ply’s, depending on the fastening method used. Rivetting allows lighter weight ply to be used, compared to bolting or screwing.

Another indication of a better-engineered table that cannot be seen after the table is completed, is the finish on the edge of the ply. A manufacturer, who is concerned with more than the superficial appearance of his product, will round off the edge of the ply so there is no sharp edge to dig into the arms when they are hanging over the edges of the table. This is important even if the table has foam around the edge, because a sharp edge can eventually cut into the foam and reduce its effectiveness.

[Q11.5] Vinyl. Australian made furnishing vinyl is designed to stand up to Australian climatic conditions, and is vastly superior to the majority of cheap imported vinyls. Vinyls also vary in surface texture and pattern. If you are particular about these things and also like a wide colour choice then you should look for a manufacturer who is prepared to make a table to your requirements, rather than limit your choices by only offering a narrow range. Of particular importance is the guarantee on the vinyl. Look for 2 years minimum warranty on the vinyl of a quality table. Refer also to the answer to question 12 below. There are also some high quality imported vinyls available. These usually come from the U.S.A. or Italy, and are generally more expensive than the Australian vinyls although they may offer some special features not available with the local products, e.g. able to be cleaned with disinfectants, extra softness, etc.

[Q11.6] Foam. The quality of the foam used in a table is the critical ingredient in the comfort of your patient. It is important to understand a little about the types of foam used in treatment tables in order to make an informed choice.

[Q11.7] A. Foam quality. The quality and price of foam can vary enormously. The price difference can be as much as a factor of 4 or 5 from the lowest grade foams to the highest. There are many different types of foam (over 30 grades) ranging from low density, through normal, standard, and high density grades, and from low resilient through to the very best high resilient (HR). Even though it costs considerably more, a quality table manufacturer would not use anything less than the best Australian made high resilient foam. High resilient foam will give you maximum deep down comfort, with full support. It is designed to bounce back to shape time after time, year after year, retaining its qualities long after cheaper materials have deteriorated, and is guaranteed for at least ten years. The foam on some tables initially feels comfortable (as in some car seats) but after you have been on it for some time you find it does not give you adequate support. Cheaper foams also tend to sag prematurely and lose their shape. Look to the length of the manufacturer’s guarantee as the definitive guide to the quality of foam used. Foam with a ten-year guarantee to keep its shape is obviously a better quality than foam with a five-year guarantee.

A quality table is an investment in comfort and appearance. Carefully check the "feel" of the foam by pushing your hand into it and also by lying on it. Cheaper foams "bottom-out" and have very little spring back. Better quality foam will spring back to its original shape. Better quality tables also have air holes drilled into the plinth so that air is not trapped inside the vinyl like a balloon. These air holes also allow the foam to breathe, reduce the build-up of condensation and odours inside the foam, and help to keep it fresh. When gauging the quality of foam in a table be sure to lie on the table as well as feel it with your hand. This is because the pressure exerted by a body on a table is quite different to the pressure exerted by the hand. In fact the pressure exerted by the hand is much greater, and this can give a false impression of the comfort of the table if not followed up by actually lying on the table. Thicker quality high resilient foams will increase the weight of your table, so unless the table is very light weight to start off with, then these enhanced comfort features are best applied to tables where weight is not an issue, e.g. in a clinic situation where the table is unlikely to be carried around very much.

As an added bonus, high quality Australian made foams are manufactured without the use of ozone-depleting CFC’s, while many poorer quality imported foams are still manufactured with CFC’s. To be sure, you should ask the table manufacturer what type and grade of foam is used in the table, and whether it is manufactured in Australia.

[Q11.8] B. Foam thickness. A thinner cross section of better quality foam will actually provide more comfort, support and durability than a thicker cross section of poorer quality foam. From this it follows that the thickness of the foam padding by itself is not necessarily a good guide to the quality of the table. Some manufacturers use "profiled " foam that is shaped like the inside of an egg carton. This allows them to state they are using a thicker (but lighter) layer of foam, although durability will be less than a thinner layer of solid foam of the same grade.

[Q11.9] C. Foam layers. Foam layers can be very useful in achieving a plethora of working surfaces. Progressive changes of density can give enhanced comfort, softness and support. Extra layers can improve on the comfort of even the best single layer foams. Softer foams can be placed over firmer foams to achieve the desired cushioning.

Unfortunately multi layers of foam can also be used to cut costs. Some manufacturers use one or more layers of low cost "fillers" in their layered construction. Relatively good quality foam is used on the top layer to give a good "feel" to the table while the underlying layers are of poor quality.

Another marketing trick is to emphasize that a particular table has multi layer foam where in fact the same density foam is used in both layers. These tables do not have the same progressive feel of a genuine multi layer table with different density foams in each of the layers.

Make sure to check the quality (is it highly resilient?), and density of the layers of foam. A manufacturer who simply states that a table has many layers of foam gives the purchaser no indication of the comfort or quality of the foam. Foam durability is governed by the weakest link, so unless all the layers are of the same quality, such a multi layer foam table may not last as long or give the same level of comfort as another table with a single layer of higher quality foam. Again the overall warranty on the foam is a good guide to its quality. D. Foam firmness. Different modalities have different foam requirements. Generally speaking the longer the treatment the more comfort is required. Sports and remedial massage therapists prefer a firmer working surface than say a practitioner in the relaxation field, where treatments can last an hour or more. Thicker, softer foams are best suited for these relaxation treatments. Chiropractors and osteopaths who perform adjustments and manipulations require very high-density foams - a very firm working surface (also popular with Alexander technique, and Feldenkrais practitioners). There are many other modalities with special requirements. A reputable manufacturer will supply a large range of foam types to suit individual practitioner needs.

[Q11.10] Upholstery. If you look carefully at the upholstery on a table it is usually fairly obvious if a professional upholsterer, or only a semi-skilled person has done it.

A quality table will have professionally finished upholstery work that is quite obvious in a table-by-table comparison with a lesser quality table. Look at the corners of the tabletop; examine the way the upholstery is done. Some tables have roughly folded corners that are simply pinned into position. These can easily snag, providing areas for dirt and grime to lodge, and are unattractive. Lesser quality tables will generally not have a sewn edge finish because normally only a qualified upholsterer will be proficient enough to master the special French stitch that this finish requires. Better quality tables will often have their upholstery work finished off with a protective edge strip around the underneath perimeter of the table so that when folded, the vinyl does not rub against itself. This also protects the vulnerable edge of the table from nicks and cuts.

[Q11.11] Adjustable Tables. There are some additional considerations that should be taken into account if the table has adjustable legs. An earlier question considered the range of height adjustments and their suitability for the practitioner. With adjustable height tables it is also important to look at the actual adjustment mechanism on each of the table legs to see how simple and positive it is to operate. Adjustable height tables normally have a different type of stay to fixed height tables, and this should also be checked for positive and simple operation as well as freedom from rattles.

Adjustable height tables normally have a steel tension cable that is the critical component in keeping the table erect. You should enquire about the breaking strain on the cable and also examine the swages used to fasten it to the table legs. The minimum breaking strain should be at least 500 kilograms. Because there are no centre legs on this type of table, the hinges joining the two halves are of critical importance; they should be extremely strong and well made. Also of importance is the degree of flex in the middle, and the overall stability. Finally check that the table does not rattle, particularly around the section where the leg extensions fit into the legs proper.