Abralon & Siaair are structurally the same, but Siaair advertises they have twice the wear as Abralon (same price). I've been buying Siaair since they became available & have had no problems.

Abralon & Siaair are structurally the same, but Siaair advertises they have twice the wear as Abralon (same price). I've been buying Siaair since they became available & have had no problems.

The structure is similar, but not the same...

Abralon has a knit backing material (think t-shirt material) and the harder, but more fragile, silicon carbide abrasive.  The more flexible backing allows the abrasive to "tear" off easier. 

SIA air velvet has a more durable aluminum oxide abrasive and is on a woven backing (think dress shirt material) that holds onto the abrasive a little better.

I am thinking the replies missed the point of the original post. My thought is the question was is 4000 Abralon the same as 4000 Saiair? Since they use different abrasives, I don't think that is clear. I think it would be close, but not 100% the same. Can anyone answer this question, as I too would like to know how they compare in this regard? Thanks.

While the abrasive material is different, the FEPA regulations are quite a bit stricter than the US/CAMI standards. This means the variations among the particles are much closer than older different standards. That said, 4000 grit is 4000 grit. Period. The variation in the results from sanding with the different pads will come from the human element and not the pad, at least the first few uses. I'd hazard a guess that for the first 3 full uses, if used by a machine, on average, the balls sanded by both pads will extremely close, if viewed by a scanner.

Thanks guys, appreciate your insight. Now I know, lol.