Sealing carpet backing to stop release of sand like particles

[scottrsellers]

If your interior carpets are rather old like ours you may notice a sand like material the carpet emits. Every owner assisted annual we've done(4 now) we vacuum up the sand which is believed to be the adhesive that formerly bonded the rubber carpet backing that no longer exists. This sand is viewable in the 1st photo below.
At this year's annual we applied two(2) coats of clear shellac to the back of the carpets which appear to have stopped further release of the sand like material. The shellac acts as a sealer.
We are planning to order replacement carpets from Airtexhttps://www.airtexinteriors.com/catalog ... at=carpets where the cost for R182 new carpets is $520. Lead times for new carpets is approximately 12 weeks.