Hello and Welcome. to Part Two (It's best if you read part one first).
Part Two -The Cot Mattress Base - Foam, Springs and Pocket Springs
British Standards For Cot Mattress Bases
This applies to all cot mattress bases; they should not exceed 10 cm deep. It was set at this depth as any deeper and there was a risk your baby could fall out of the cot when it was on the top setting, or climb out when it was on the low toddler setting. You may see cot mattresses advertised at 13 cm deep, but this is nothing more than a marketing ploy to make you think the deeper a cot mattress is, the more comfortable it is. But please do not be fooled; generally these mattresses are made of the cheapest foam. It's always quality not quantity that wins the day!
All Foam Cot Mattresses
These are made from a block of foam. How long it will last and the support and comfort it will provide really depends on the quality of the foam. It's always important to remember that foam as a product does not like heat weight and damp which is unfortunate, because that is exactly what a baby is! So the cheaper the foam, the poorer the quality and the more it will be affected by heat weight and damp and the more chance it has of dipping or denting and not giving the required support.
We will discuss quality of foam later. In some European countries they do very clever things with foam. They may sculpture it to give a posture pocket feel and to make it more breathable. They might use different qualities to offer more comfort and support. We tried this idea here in the UK 15 years ago but it didn't take off - it seems us Brits like springs!
Sprung and Pocket Sprung Bases
These sprung units are encapsulated in foam. The principle is that by using 50% less foam you reduce the heat because foam is an insulator and air flows through the springs. These cot mattresses offer more comfort and durability with the springs supporting the foam.
Sprung bases are cheaper than pocket springs; however they do not offer the same level of comfort, nor do they last as long.
There are two main types of pocket springs, ones that are linked by length and width and ones linked only by length; the latter do not give the same support. How can you tell? Well you can't unless you put weights on them! However, you might suspect cot savings are being made if the price is too low.
The springs are covered with a 2 cm layer of foam top and bottom and a foam wall at least 6 cm wide.
Let's first discuss the top and base.The springs are 6 cm deep and the foam top and base both 2 cm deep, adding upto the British Standard of 10 cm. (2+6+2=10)
The thin 2 cm depth of foam has to cope with the weight of a baby from above and the pressure of springs from below and continue to do this 12-14 hours a day as your baby grows heavier and more active.
Basic quality foam will not give the best support and will be more liable to dip or dent. Good quality foam will give a comfortable supportive sleep and it will certainly be durable and last your baby the 20,000 hours from birth to toddler until they go into an adult bed.
Currently, the foam used to cover cot mattress springs by most chains stores, department stores and some internet companies is rated at 24/130 or equivalent quality, so it passes the British Standard. Some cheaper mattresses are made with even a lower rating, but they will show signs of denting well within a year.
This is How Foam is Rated?
Lets take the average foam. It is 24/130 -The first number "24" is the weight of the foam per kilo and indicates the density or the foam, which affects the durability.
The second number "130" is the amount of pressure in Newtons it takes to compress the foam to 40% of its size. This measurement is called Indentation Load Deflection (ILD) which assesses the firmness or the feel of foam, how it yields to weight and pressure and how it returns to its original shape after compression.
Now, we wouldn't use 24/130 foam in our cot mattresses; over recent years we have been looking for better performance so they can be guaranteed for 5 years. This is all part of the future, making products that last, rather than ending up going to landfill. We will discuss this in depth later. Our pocket sprung NightyNite® baby mattresses use 30/150 foam - this is a huge step up in durability, support and comfort.
For the past 15 years we have also produced a pocket sprung mattress called the "Nightynite® Excellence." This is made with 50/215 foam and we're proud to say that nobody else in the cot mattress industry uses such a high quality foam to encapsulate the springs. Later we will be discussing the advantages to your baby and the planet when using such a high quality component.
Cot mattress - Foam Perimeter Edges
When your toddler stands up against the cot side, their feet are not on the springs but the side of the mattress. Obviously they create more down force to one area when they are standing. The sides of the mattress need to be firm and supportive so that their feet do not crush the foam and slip down between the side of the mattress and the firm side of the cot.
Memory foam is not for cot mattresses. It has too many extra chemicals; it can cause over-heating and pooling and is not really worth any further discussion.
So, next week I will be discussing natural cot mattress bases involving coir, lambswool, latex and springs and also, the use of fibre made from recyclable plastic bottles.