OK, my test infusion of three different core materials went very well..!
Preliminary results (Pictures
and precise measurements will follow 
)
I did a completely parallel infusion by putting three strips of core material side by side in the same stack with the reinforcement.
The infusion setup was with infusion mesh only at the wacuum and infusion ends, only CF fabric, core and peel-ply in the center.
The previous info was not quite correct however.. The 3D-core I have is 3 mm, and the floor-cork and Soric is 2 mm..
I tinted the IN2 infusion resin with translucent blue, to be able to see the resin in the core when cutting up the samples.
After 24 hours and a 2 x 2 hour double post-cure at around 80 deg., I demoulded the laminate
I cut the single laminate into three strips with exactly the same dimensions, one of each core material, and tested from there.
Weights for the three identical sized samples were. (The three samples were set up in my milling machine and milled to the exact same size, i can not measure any difference with my calipers
)
3-D core: 37,66 grams
Soric: 35,75 grams
Floor Cork: 31,45 grams
The Cork-core laminate is definetely lighter, and seems to take up less Resin, but since I infused all three in the same go, I have no direct measurement of the resin uptake, however the cheap floor cork also did not infuse as well, leaving a slightly resin starved front side with distinct pinholing.
the 2 mm Soric did the absolutely best job, when it comes to cosmetic appearance, virtually no pinholing, close to perfect infusion.
The 3 mm 3D core did not do as well as the Soric, but better than the Cork, but bear in mind that this was 3 mm core, as opposed to the 2 mm of Soric or Cork.
All three core materials left absolutely no print-through on the front side (but the mould being plate glass, probably prevents this.)
On the back, the 3D-core left a very visible hexagonal print, very easily felt by hand even when the peel ply was removed.
The Soric left a much less deep and much smaller hex-pattern.
The cork left only a slightly uneven random "distortion" that can only just be felt by touch.
I did a stiffness test using a weight and a 1/1000" indicator dial setup from my lathe .. This showed no real diffierence in stiffness between the Soric and the Cork, while the 3D core was almost a third stiffer.. Looking at that from a purely mechanical point, most of that can be explained merely by the 1 mm thicker laminated core.
I have not yet tested the crush resistance of the 3 laminates, but I will do that later this week.
My conclusion is that the cheap floor-dampening cork is perfectly usable for infusing non-critical panel parts.
Car panel parts, mud guards e.t.c. can be made with this material. The cost is considerably less than Soric, and only about 1/10 of that of 3D-core.
If you want to make "green" cored panels, a combination of Jute/flax reinforcement and cork core would be very CO2 -friendly I think....
I do not know the prices of the Cork-core specifically made for composite work, but it may well be cheaper than Soric.
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