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Pocket springs – The arguments

This comment was submitted by a reader who raised an interesting and valid point about the use of Harrisons Posturfil and HD mini springs as a viable component to supplement the upholstery layers. In order to make for easier reading, I have added my responses directly below each point. 

Please use the Ask us function to raise any additional questions on springs or mattress components.

Minisprings DL This is supplementary to his original line of questioning but reading our article on pocket springs explained will help to put  this comment into perspective.

Are slatted bases suitable for heavy pocket sprung mattresses?

2013/02/25 at 18:07
Hi John and Ryan,
Thank you for providing such an informative, generous and brilliant website. Also, for answering my questions so quickly. Wow!!

I’m glad you enjoyed the questions! I certainly found your answers both informative and enjoyable. (Thank you). Also very thought – provoking, regarding springs.

It is now very clear to me that you need to consider all the variables together, and not base your choice on one factor. I must say, though, that your answers to individual points on comfort and support are all very helpful, in their own right, and this post is really about the support aspects. (I’ll be sure to also consider your advice on toppings as well).

I wrote this post because we intend to buy a new bed frame and also a new mattress in the near future. (The cheaper mattress which we recently bought, is just a stop-gap, and will become the guest bed when we move house.) So we do have to go through the whole selection process, and it’s a good job we found your site first!! :-)

We’d be very grateful for any further comments on whether a slatted base would be ok for a new and “good quality” heavy pocket sprung mattress, (and if we choose this combination, should we add anything else) or if we should really change our thoughts to a sprung edge divan. 

John Ryans Response

It annoys me immensely when I see mattresses described as ‘For Bedsteads’. This is a fairly new marketing technique and the only reason I see this used is another avenue of potential sales. I have a slatted bedframe and Ryan has a Sprung Edged Divan. There is undoubtedly a difference in overall comfort level. The SE Divan Base being the better option as the spring edging in the divan offers a considerably greater degree of suspension for the mattress.

Bedframes, either flat slatted or sprung slatted, do not offer this degree of suspension and so the resilience of the mattress is impeded (less forgiving). Divan bases are not the most glamorous of items and so the compromise you will have to make is between Form or Function.

We are currently looking to manufacture a low-level spring system to sit directly onto slatted bases (a mini mattress if you will). This will be able to offer the suspension qualities of a sprung edged divan for those of us who like the design aesthetics of a bedframe.

The slight downside to this addition will be an increase in height to the overall mattress and spring combo. Some bed frames are designed so that the tailboard is slightly higher than the mattress so the thought has to be put into the overall look of the finished bed or purchase the frame with this in mind.

As a justification for this response, And So To Bed (high-end retailer) offers a selection of well-crafted bedframes and it is unlikely they will insist that only the Vi Spring Bedstead mattresses they supply will be suitable for their bedframes. 

What are the pros and cons of Vi-spring and Harrisons spring manufacture method?

Also, we need to consider further, the pros and cons between the Harrison type and the Vi-spring/your own type of construction. Bearing in mind that we can balance the upholstery by careful choice of topper(s) but cannot alter the support springs, other than by choosing what is under the mattress.

John Ryans response

It has to be borne in mind that Vi-Spring and Harrison’s manufacture their mattresses utilising two completely different methods of construction. Vi-Spring stands by their hundred-year-old heritage and known as the first manufacturer to utilise a pocket spring  system.  Harrisons have their own spring manufacturing company (Spinks Springs) and obviously will take a different tack using spring technology to improve on what is currently out there.

For someone to categorically state whether one system is better than the other would be rather churlish. There are valid arguments on both sides and no doubt Mt Harrison and Mr Vi Spring could discuss at length the validity of their own methods and viewpoints of construction.

For this Keith, it would be rather unfair of me to comment further before you give these respective manufacturers the opportunity to justify their own construction methods themselves. Once you have their responses to this particular question I would be more than happy to offer my opinion. 

Does the diameter of a pocket spring wire affect its stiffness?

OK. now to the springs. You raised several very interesting points, especially about the layers of support springs, including the observations you were given by a spring manufacturer.
I have an engineering background, and you’ve prompted me to look up some basic spring theory, and have another think about this. (What a minefield, and it raises more questions than answers. !!!) I’d be interested in anyone else’s ideas as this is just my theory:

In a coil spring, it’s stiffness (spring rate) is affected by the material it is made of; the thickness of the wire; the diameter of the coils; and the number of active coils (coils that are free to deflect). Reducing the diameter makes the spring stiffer. Reducing the number of active coils also makes the spring stiffer.

John Ryans response

The first part of your comment is right. The thickness of the wire (gauge) does (obviously) influence the overall tension. The question is, how many of these springs becomes the optimum number? For example, will 1000 pockets of a certain spring tension be enough for a particular users bodyweight – Or, will 2000 provide you with a more ‘comfortable’ mattress?

The second part of your comment asks will reducing the number of active turns make the spring ‘stiffer’? I personally don’t think it does, and again it all bears on the actual gauge of the wire used. If we look at Hypnos Beds as an example of this, they utilise the Ultrasens™ pocket system within their top of range mattresses. The top of range Sandringham uses a 17 turn spring and their Baroness utilises a 10 turn (Ultrasens) spring.

Going down in their range they then start to utilise their ReActive™ pocket springs in their mattresses. The top of the range in this sector utilises an 8 turn spring going down to 6 active turns in their Regent model. Within their Orthos Collection, they utilise ReActive™ 10, 8 or 6 dependant on the model. However, these are only available in Firm or Extra Firm tensions.

The Ultrasens™ spring is a patented design only used by Hypnos, Look at their site in order to understand the design features of this particular spring [Here]. I believe the ReActive™ pocket spring they use is the traditional barrel shaped spring (I cannot find any descriptive reference to this) and I would be inclined to ask them what the difference / benefits is / are between their ReActive™ pocket spring and the 6 turn pocket Vi-Spring utilises. Additionally, the most intriguing question would be, can the difference in overall support between the Ultrasens and ReActive springs be measured? Can the difference in price between models using these different spring types be justified?

Vi-Spring utilises a 6 turn spring right through their entire range in various gauges, diameters and counts. Taking into consideration their top of (core) range Magnificence retails in the region of £17.000 or indeed their Majesty (Harrods exclusive) retails in the region of £50.000 it begs the question, is a 6 turn pocket spring ample? I would ask you to question the appropriate manufacturers this quite concise question in order to get their view on this.

Will a firm 2000 spring mattress have to use thinner gauge springs compared to a firm 1000 pocket spring mattress?

We can assume that springs used in a pocket-sprung mattress all have a linear spring rate. This is because they look as though they would not “bottom out” during use. (Variable rate springs have some tight coils which are designed to bottom out and become inactive after some load is applied. This leaves less “active” coils, making remaining movement of the spring stiffer, under an additional load.)

Let’s assume that all mattress pocket springs are all made from the same steel material, just to make things easy. We are also led to believe that they are all made from 3 common gauges of wire.

A manufacturer can control the stiffness (support) of a mattress by using any combination of (a) more/less, smaller/larger diameter springs across the area of the matt; (b) by using springs with more / less coils; or (c) by using different guage springs.

Let’s look at an example question, that a consumer might think about, when trying to guess what benefits they could get for their money when they are being influenced by the manufacturers’ adverts:

Q: Will a 2000-spring “firm” mattress have smaller but lighter gauge springs, than a 1000-spring “firm” unit, and should it feel the same or more or less supportive? This is something that only the manufacturer would know, from their design process. I suspect that the higher spring count may theoretically give a more “finely detailed” contour in its support, but given sufficient wadding, would this make a real difference anyway? Who knows?

John Ryans response

Interesting question. The gauge of the wire can be the same in a 1000 or 2000 unit. Theoretically, the more springs as you say will give a more finely detailed contour to the sleeper. The theory I liked was the bowling ball analogy. On 1000 springs the ball would be using say nine springs. The centre of the ball (pressure point) would be depressing the centre spring more than the surrounding eight springs dispersing the load. On a 2000 unit, the ball would be using say 18 springs. The centre of the ball (pressure point) would be depressing 4 springs with the remaining 14 springs dispersing the load. Theoretically, the four springs on the 2000 unit will not be depressed as fully as the one spring thereby providing less resistance.

Taking this theory a step further, does that imply that a double layer of 2000 springs gives the support required but, less than twice the resistance of a 2000 unit? If so, at what point does it stop? Like I said in response to your previous comment Keith, someone with a good understanding of engineering physics will be able to pinpoint more accurately a simple explanation to the optimum spring count vs load thesis.

Do mattress springs all have an equal support rating?

I guess that only someone with your own experience and a lot of time for testing, could test several combinations and make a general conclusion to compare between models in a range, or between manufactures. Even then, I guess it would be quite difficult.

The amount of support in a mattress could only really be known, and compared, by the consumer, if manufacturers provided a “support value” identifying how much the mattress springs will deflect if a given weight is applied to a given area, for each model.

John Ryans response

Absolutely. Our plans for the future site is to include videos bench testing various spring types using various weights to see how each performs. Currently, we can only speculate and theorise. The Support Value for a given body weight would indeed be much more beneficial to the consumer than the ridiculous SMoF (Soft Medium or Firm) description so prevalent throughout this  industry. 

Do all mattress manufacturers follow an agreed standard set of spring tensions?

I suppose that a less detailed approach could be to ask you, if:
(a) Do any (or all) manufacturer try to balance out the factors so that all their own “firm” mattresses have the same support and ditto for “medium” and “soft”?

(b) Is there any industry standard that means that “firm” “medium” or “soft” will give very similar support between different makes of a mattress?

John Ryans response

In short No! or at the very least, unlikely. There is no industry standard for SMoF. When I first started to look into this I couldn’t understand how a mattress could be described as SMoF without knowing the end users actual bodyweight. Being the sceptic I am, I suppose it is in the retailers interest for you not to know the Support Values. I envisage the consumer asking the retailer will (this particular mattress) be right for me? and just get a resounding Yes and a sale.   So how can this anomaly be rectified?

As a secondary viewpoint on this, it has to be understood that overall support / tension is not wholly down to the springs used. You could have a mattress with identical springs but by using different combinations and levels of upholstery will give you a completely different level of comfort.  This is quite an arguable subject and no doubt there are many points of view. My own viewpoint is that a retailer with knowledge of construction methods and how each component works with each other coupled with knowing a persons body weight ‘should’ equal the perfect mattress. 

Will double rows of smaller springs provide a different tension to a single row of springs?
OK, so onto double rows of springs… I had a think about this.

Basically, let’s take (say) a 6-inch spring, which will be compressed 1 inch by a 20lb weight. (spring rate 20lbs/inch). Now, cut that spring in half, to give you two 3″ springs. Put these two halves end-to-end, (and basically you still have the same spring). Add the 20lb load, and you can imagine that the total 1-inch compression will be divided between the two shorter 3″ springs. Each half-spring will compress half an inch under 20lbs load, (spring rate 40lbs per inch for each spring). ( note that in each spring you’ve  halved the number of active coils to double its stiffness).

Now say you have another 6-inch spring, half as stiff as the original.(10lbs per inch) and do the same thing. A half of this spring will become a 3-inch spring with a stiffness of 20 lbs per inch.

Here’s the good bit …. now put two different half-springs end-to-end. 3″ at 20lbs / inch and 3″ at 40 lbs/inch. Again, compress this combination with a 20 lb weight. The first spring will deflect 1″ and the other will deflect 1/2 ” .. a total of 1.5 inches. Resultant spring rate is 13.33 lbs/inch.

That sounded complicated, but what it tells us is that by using two different strength half-length springs, in different combinations, you can achieve three different total spring rates. Wow, what a complicated way of doing it, though!

It also illustrates that you do not get a variable spring rate by butting two different springs end-to-end; just a different strength.

I’m sure nobody would bother to actually cut springs in half, so the half-length springs must be made separately. Perhaps a stock of several different stiffness half- length springs in the factory would allow a manufacturer to build a custom made mattress with a wider variety of stiffnesses, or with different support for each sleeping partner? But this could also be done by simply using a wider variety of full-length springs, too. I wonder if there is a cost benefit to the manufacturer?

Is there some other (real) benefit to these double rows, (I’ve never seen one advertised!), or is this maybe a gimmick to add more price than worth? Comments from anyone on this would be most welcome …

John Ryans response

I can understand completely your train of thought here but I do think we are over analysing this and only a bench test could conclusively confirm or disprove the theory. Something for a later date perhaps. My own views on the double spring layout is borne from our introduction of our Artisan Bespoke 002. Between the two layers of springs there is an insulating layer of Calico clipped to the outer springs – otherwise there may be a tendency for the loose springs on top to work it’s way through and fall between the underlying springs beneath. You could view this insulator as the ‘barrier’ to withstand the main compression of the user and therefore, the top layer of springs is taking the bulk of the pressure applied.

The double spring technique can also be seen as adding an additional level of suspension and particularly more so if partnered with a sprung edged base which offers a further element to this.  I do hold the viewpoint that progressive suspension of all components including upholstery layers offer a greater degree of comfort and longevity. People often ask why we use two layers of latex in our Origins Pocket Latex rather than just one layer of the same combined thickness and really it boils down to theory – being that there has to be an end point where one component reaches it’s optimum tension before the secondary layer kicks in. This applies more to different layers of upholstery rather than latex but we apply this principle to the latex just in case. Upholstery within a (good) mattress is built up with the firmer elements at the bottom directly above the springs and gets progressively softer to the top of the mattress.

Going back to the double spring technique, it could be viewed in the same way. The first layer of springs will reach optimum load before the secondary layer starts to kick in. Looking at your next question I think I will carry on this conversation there. 

How necessary is Harrisons revolution spring?

Ah, now Harrison’s Revolution spring……
I guess that the spring-in-spring theory is that the outer spring must be compressed by some amount of force before the inner spring is contacted. At this point, additional deflection from a further force is resisted by both springs in each pocket.(ie the mattress becomes firmer at this point). I’m sure this must work in both theories and in practice.

The real question is, “What difference should this make to things which affect the sleeper’s posture / sleep experience / etc.?” I can see that for a given firmness of mattress, a very light person may perhaps not deflect the mattress very far, deflecting mainly the lighter springs, whilst a heavy partner, instead of sinking very deeply, is supported more firmly when they contact the second set of springs, thus reducing the amount that they “sink” any further.

The big question for me to ask, though, is that given the “right ” amount of support for the sleeper, would this two-stage support system feel any different, and what do the manufacturers propose as the benefits when compared to a simple pocket spring, also giving the “right” support?
Your own considered opinion on this would be much appreciated.

John Ryans response

Once again, Keith, I do think this question should be initially directed to Harrisons before I make further comment. It is viable and well thought out premise. I would also couple this question to the comment you make below. 

Do micro springs provide more comfort than traditional upholstery fillings?

Nearly finished! … Harrisons Posturefil and HD.
I think you have answered my query mostly, by your first comment.

I believe from Harrison’s blurb, that these springs function as part of the comfort upholstery. ( Am I right?) So the main question is, I wonder if you are able to comment on whether these tend to give more or less comfort as compared to a similarly priced mattress with a similar amount of support, but with more wadding instead of the Posturefil & HD springs? We have a really detailed article on HD springs here.

What I’d also like to find out, is, what the supposed roles of the two items are. (Just because I’m intrigued) They come in various combinations, and with variations in the wadding, throughout the mattress quality / price range. They must be different to each other. Or is this perhaps a perceived Worth / Price thing?

The second question I suppose, is, that when considering the comfort layers of a mattress generally, what are we hoping to achieve? Something that feels “soft”? Something that moulds to our shape and stays there? Something that moulds but is springy? Something which firmly supports those parts of the body which are not pressing down on the support springs? Takes pressure off the parts of the body that are taking most of the weight? Helps us to move easily / or stop us moving? Or what?

And in the case of these little springs, the question then becomes, “which of these attributes would they be good at, and which would they not? ”

John Ryan response

This last portion of your comment is the key to your original line of questioning and couple this to your question above about Revolution Springs would make for very interesting reading when you get a response off Harrisons. There is no doubt about it that the Revolution Spring system has its benefits. However, does the introduction / addition of the HD and / or Posturfil springs improve the overall feel of any particular mattress and if so what is the optimum number that will do this?

The Spink and Edgar Empire, as I have said before utilises a total of 21,700 springs (Revolution and HD – RRP: £15,171 [KS]: (Mar 2013)) in the mattress alone (4000 in the base). If this is the optimum number which is in their top of range mattress – How much of a compromise if any, is the customer making by opting for a mid range mattress – say the S&E Elegance (£1,877 [KS] March 2013) which utilises a total of 4500 springs in the mattress alone?

The perception a reasonable person would make of this is that the more springs equal the better mattress. If this is the right way to look at this, it begs a further question as to how much of a difference in comfort for the price paid can one expect to compromise?

Will mattress tufts compress over time?

I do note that traditional tufted mattresses have a very uneven surface when new … very compressed at the tufts, soft and full in between. Obviously, the soft areas become a bit compacted over time, and the unevenness can be bridged with a topper. Should a good mattress “even out”, or stay high in between the tufts? And, coming back to the Harrison springs, Would these be likely to retain their springiness, longer than traditional wadding (in a similarly priced mattress of course)?

John Ryans response

The undulations on the mattress will indeed flatten out over time – they are supposed to. New upholstery is always at a premium loft when new and settlement, particularly on natural fibres is an intrinsic part of the bedding in process. This should be a slow process and the more you can do to slow down this process the better – hence our obsession with toppers. This also brings me to the anomaly about trying mattresses in store. What a person feels from day one is not the same as they will feel some months down the line. Like new shoes, all mattresses need to be broken in (slowly) and will get more comfortable as time goes by.

I have no doubt that mini springs will retain their ‘springiness’. The most obvious question to this would be are springs better than horsehair to provide the resilient layer within the mattress? Horsehair being the natural equivalent of a metal spring. Again, another question to ask Harrison’s for an alternative and welcome point of view.

Summary

We understand this was so long and complicated, but you have got us intrigued, and we’re finding this subject quite fascinating. It’s certainly true what you say that there’s so much you need to consider with spring tensions, wire diameters and numbers of turns and that there’s such little information freely available.  If you need help with springs or mattress components give our small expert team a call to assist you.

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