Self-Inflating Mats & Minimum Thickness

@Andrew_I
My Prolite 3 S is 327g without the bag. (Spec is 310g).
I got it as a warranty replacement for the previous iteration which was about 410 grams (it was more rectangular rather than tapered and different fabrics).
Up until 2015 all I used for years was the short Prolite SI mat, supplemented in winter with a full length CCF pad.
I’ve mostly been on inflatables for the last 10 years or so, I do still use the PL3 on some summer trips of up to a week. I like the simplicity and speed of deployment/packing. But I definitely don’t sleep on it as well as I do on my Thermarest Neoair Xlite Reg. Maybe if I was doing a very long trip my body would adjust again.

My Prolite 3 S is 327g without the bag. (Spec is 310g).

Indeed. That generation of Prolites were heavier than the 2012-2014 model. Then they got heavier again in 2015. The 2012-2014 model had a rounded head and foot end (not the semi-rounded of the earlier Prolite 3 & 4’s). The 2012-2014 were orange on top, and grey on bottom. The Prolite 3 or 4 designation were earlier and heavier. Also, the “plus” models from any year were heavier, being 1/2″ thicker.

Clear as mud :)

Yeah!  Exactly!

Okay, 327g isn’t that much bigger than the 310 g spec, but it’s annoying.

I think some of the problem is they would improve a model to fix the delamination problem, but they didn’t change the official model name.  I think it’s because they wanted to limit liability for delamination, but that’s just a guess.

I still love thermarest products – it’s not that it’s self inflating, but the foam that allows self inflation also makes it more stable to sleep on.

the foam that allows self inflation also makes it more stable to sleep on.

Exactly. That is what made them popular in the first place (and why they still sell them). Self inflation really doesn’t matter. But the foam adds comfort. It is just heavier for the same thickness compared to inflatables. (Or it is thinner for the same weight if you want to think of it that way.)

Over on Reddit there is a guy who is playing around with making self inflating short pads.  He uses nylon coated with TPU and heat seals the edges and bonds the fabric to the foam with a hand held “iron”.  This has me intrigued. The lightest fabric available seems to be 70 denier.  He plays around with different thickness and density of foams.  It seems like an opportunity if a form of tech fabric was found to make a very light pad.

What does he use for a valve

There is fabric and glue-in valves to be found at diypackraft.com. And inspiration.

when I sleep on snow, I have to add a CCF pad for warmth

sleeping on snow, the temperature of the bottom of the pad next to the snow is 32F

when I sleep on not snow, I’ve measured the temperature in the morning.  Bottom of pad is 50F even though it’s below freezing air temp.  The ground has some insulation value to it.  It also has heat capacity so it takes a while to warm up.

There is one simple answer to all questions of the “why doesn’t some manufacturer make xxxxx” type: because they do not think they will make a profit on it. There may be several reasons why they don’t think they will make a profit – too little demand, too high a cost, too little durability – but it still boils down to that. And of course, they could be wrong. But not usually. The market rules all.