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Liners Print E-mail
In our experience, liners are the easiest way to seal a pond.
When combined with Fleece900 and possibly even with composite mat this sealing becomes rock hard and practically indestructible. This makes it superior even to concrete.
It is important, however, to choose the right materials for the corresponding application.
Most liners are made from PVC, PE or rubber. Whether it is good or bad depends on the application it is used for: A screed underlay, that lies in a well protected room floor and doesn't have a crease, will never be exposed to UV light and doesn't need frost protection and so on. Material that is good for this application is totally useless as a pond liner, though - even then it is sometimes sold as such...
Liners vary in flexibility. NaturaGart Green is especially recommended.

NaturaGart's Special Liner
On some days we sell more liner than a medium sized garden center in a whole year. That is why we can establish specifications such as better frost protection, toughness, colour, etc. This is how the NaturaGart Green liner is made: Branded and made to our specs.
If you need less, you have to buy whatever the dealer has available from stock, and the quality of materials may vary greatly.
The green NaturaGart Liner is made to our specific requirements and has 'NaturaGart' imprinted on it.
Qualified liner technicians can make liners with (nearly) any property - they cannot, however, combine them all. Normal cold snapping temperature is -21ºC. We require -45ºC. More is not possible because otherwise, among others, the UV-resistance would be compromised. Many characteristics are mutually exclusive. So be careful if someone promises '100% UV' and 'unlimited frost resistance'. They are trying to bamboozle you...

Important Liner Properties
It is really impossible to 'feel' a liner's properties that are important over the long term. Some properties give an indication. These are the most important ones:
Break Elongation
NaturaGart Green reached 350%, whereas simpler liners make just over half that value.
This stress value drops over time.
Tear Spreading Resistance
Some liners can be torn like paper once they have been damaged.  
Cold Resistance
These values are only applicable to factory new liners and gradually drop toward zero over the years. The standard value of -20ºC is calculated to last 10 years. By that time the liner's cold resistance has reached about -10ºC, a temperature that can be reached more easily. NaturaGart liners, too, lose their cold resistance - but they begin their aging process with -45ºC resistance, which means that critical temperatures are reached much later.
Two separately manufactured liners are bonded together across their entire surface. The reason: If one liner has any production faults that may compromise its durability, it will never affect the whole thickness of the liner, but only half at most.
Liner Repairs
This is a problem for PE and EPDM liners, and cheap PVC liners loose their adhesive capabilities due to too high proportions of filler materials.

Find out more about the important properties of liners here
Plasticisers Migration
Next to the technical properties, plasticisers determine a liner's durability: In PVC liners the single molecules are connected with 'hinges'. There are many different types of these hinges. It the plasticiser-hinge leaves its position that spot becomes hard. It this happens a lot, the liner becomes crumbly. Also, many plasticisers are poisonous to the point of even damaging DNA.
Many fish spawn have died due to poisonous liner.
Small 'hinges' with weak binding strengths leave their positions easily. The 'slip' out of the liner. Such plasticisers are very simple and hence cheap. This results in brittle liners that break.
Better plasticiser hinges are stronger and cannot easily leave their position. Such molecules have a more complex structure, consist of branching chains, that tend to get caught. The result: The Liner remains flexible for longer.

Hundreds of Types of Liner
Any rag of liner can be called pond liner, because the term is not protected. Hence there are hundreds of different makes in the market. These are the three most important groups:
PVC Liners
These liners can most flexibly combine different properties: Anything from a short lived cheap product to a high quality long term solution is possible.
NaturaGart Green
Usually the most sensible decision. For most ponds 1mm Green + Fleece900 gives the best price to quality ratio.
NaturaGart Black
The better among the cheap ones. If you know that you will move sometime or if longevity is not that important.
Find out more about PVC liners here
PE Liners
are manufactured by 'blowing' tubes and then cutting them open. This allows to make seamless widths of up to about 8m. If liners of this width only have to be cut from the roll then this is often the least expensive solution.
On the other hand: This material is stiffer and cannot be securely glued! Any damage easily means total loss.

NaturaGart PE
This material is only really suitable for very large, evenly shaped basins such as our Scuba Park. Because of its stiffness it causes problems in smaller spaces. One problem is the difficulty in repairing it which is only (temporarily) possible with hot air or with adhesive strips. Find out more about PE liners here
Rubber Liners
This covers a whole family of products. The extremely elastic butyl liners are chemically sensitive to carbohydrates and are not suitable as pond liners from our point of view.
EPDM rubber in many forms is also used. It is chemically very stable, but difficult to glue. It is very elastic, but tends to tear like paper once it is damaged.

NaturaGart EPDM

Only sensible when using rectangular shaped liners. The rubber is then comparable in price to the thicker of the green liners. Lay carefully because even small damage leads to large tears.. Read more about rubber here

This is a comparison of the most important properties of liners
Property NaturaGart

Cheap liner*
* According to competitor's brochure
Tensile strength
lengthwise 19.3* 17.5 12 8 18.5 *Ideal values for NaturaGart-PVC und PE
18.7 16.5 12 8* 17.5 *EPDM doesn't handle point loads very well
Tear elongation (%) lengthwise 346 %* 310 % 200 % 310 % 730 % *much more flexibility reserves than cheap liner
  transversal 363 % 315 % 200 % 310 % 730 %* *Best values with PE
Tear spreading resistance (N/mm) 110 95 75 11.7* 139 *damaged EPDM tears like paper
Repairs well well ?* adhesive tape
hot air
*can often only be glued for a few years
Flexibility good good often good
very good
stiff* *therefore not suitable for smaller ponds
Resistance to ageing
good* acceptable* often problematic* very good* very good* *extremely dependent on installation conditions
Resistance to cold -45ºC* -30ºC -20ºC very good
sensitive** *very important
**eg. transport
How to Assess Price and Quality
Extreme durability and near indestructible products of course have a higher price.
On the other hand these properties are not always asked for.
The NaturaGart product range allows you to stepwise adapt your security requirements to your budget.
When budget is limited
or technical requirements
as regards liner quality are
NaturaGart Black

Somewhat more security:
  NaturaGart Black
+ NaturaGart Fleece330

With stones and roots it is better to use:
  NaturaGart Black
+ NaturaGart Fleece900
More sensible for better durability:
  NaturaGart Green 1mm
+ NaturaGart Fleece900

For even better durability
 NaturaGart Green 1,4mm
+ NaturaGart Fleece900

For very large ponds and special cases:
  NaturaGart PE or EPDM
+ NaturaGart Fleece900