Different Karrimats?

[Moondog55]

A question for the more mature and experienced members.
I have some old Karrimat here in the Yellow and I was wondering if anybody knew the technical specifications of the other iteration?
There were 2 versions, the Yellow standard version and a green Expedition version that was thinner.
To the best of my knowledge both were Evazote but the green version was thinner. Possibly a density difference but as I never owned one I have no idea.
I am in need of some durable foam for a tent floor for next winter and I want something much more durable than the cheap blue foam from Clark Rubber, I also want thicker and warmer than the thin Exped mat sold by Bogong in Melbourne

[Mark F]

If I remember correctly the yellow ones were made in an autoclave? mould and the cells were a single gas rather than air - nitrogen comes to mind. The other Karrimor mats were slit from foam blocks like the blue mats.

For a tent floor you could do a lot worse than those 500 x 500 clip together foam squares. I have noticed them in a quite thin version.

[stry]

I have a blue one and also a blue and yellow one, the two layers of which may be of different densities.

I also have a UK Multimat. The squish test between finger and thumb suggests that the blue Karrimat is the stiffest/densest of all three, with the Laminate Karrimat a close second.

I also have a quite dense generic mat which was sourced from the furniture industry in Aus 40 to 45 years ago.

For a floor, I like Mark's suggestion. Neat, tidy and won't slide around like separate mats. As an extra sleeping layer under a more modern mattress, I like the Karrimor. If you decide to go with mats, I could probably let go of one or two for the price of postage.

[Franco]

Some info here : https://www.outdoorgearcoach.co.uk/blog ... mat-story/
That I in "I invented" is Mike Parsons.
On another site I found the comment that it was "pressure-blown" foam , however according to Mike he cut those mats from (I suppose) foam blocks.

OK, I found more info from Mike Parsons :
I invented the Karrimat in 1968 using Plastazone and shortly thereafter with Evazote which was produced in yellow (specifically and exclusively at that time) for me at Karrimor; Karrimat is now a generic term for closed cell mats in several Euro countries but was the reg;d T M of Karrimor in the UK of which I was then part owner and the key designer.
1968 was very shortly after the invention of the material, in UK which to my knowledge is still the only place where its made. Although the unique mfg process is lengthy and more expensive than other foams made by extrusion processes, zote foams have maintained their position because of higher performance.
Plastazote is polyethylene (or polypropylene?) and has less rebound than Evazote which has vinyl added to the long polymer chain.
Evazote has better compression recovery, tear resistance and ( subjectively) feels slightly warmer because your body sinks into it ever so slightly. Both are available in a range of different densities, Karrimat ( from memory) was always 45kgs.
The original process for making these closed cell foams was ( and probably still is) a lengthy, ie more costly batch process like making a loaf of bread. The rectangular hard plastic pieces were placed in a pressure chamber and Nitrogen pushed into it in gaseous form, after that the 'bun' was then placed in an oven and the gas emerged as distinct unconnected bubbles ( hence 'closed cell')
This bun was around 30mm thick and had a skin around it and was then sliced into different thicknesses, leaving the outer surface cells open, which cld be sealed if necessary.

Hope this adds slightly to the understanding, however I cannot at this precise time talk definitively about comparative R values but in due course will do so within the new book a team of 7 are working on, (6 in UK one in USA)
"keeping dry, Staying warm; through all activities over 7 continents"
http://www.outdoorgearcoach.co.uk/

[Moondog55]

Thanx Franco/Marc/Stry

The fact that the yellow mat was 45kilo foam means that the thinner green mat was probably denser but at the moment the product only goes up to 50kilo per cubic metre
Just being denser is probably why it lasts so long.
A full 30mm thick "bun" would have been very warm wouldn't it.

[stry]

Very warm I think

However rolling it up and packing it would a wee bit difficult

[Moondog55]

Having worked in that industry for a very short time it's probably a misprint. when I worked at Bostik & Dunlop the buns were around 300mm or more thick, so 30cm not "mm" Although they were different foams the sizing would be similar

[Moondog55]

I'm also chasing the material to replace the cheap CCF pads in a couple of frameless day packs. The soft blue foam doesn't work all that well for that. Yes to the idea of the jigsaw mats for the floor of a big tent, that would work better than the cheap blue mat from Clark Rubber

[stry]

Foam has automotive gasket/sealing uses also. I have a bit here somewhere that is maybe 12 mm thick and appears to be closed cell.

Might be another rabbit hole to go down in your hunt for something suitable for the packs.