Use of Starch Based Blast Media for Dry Paint Stripping 932616
In the 1980's, several processes emerged as possible replacements for chemical strippers containing methylene chloride. A viable process appears to be dry mechanical stripping using wheat starch. It is seen as promising because of its gentle treatment of aluminum alloys and composites.
The process itself is reported to be operator friendly, with no fiber or primer damage even with multiple blast cycles. The media has been tested by Boeing Commercial Airplane Co. and is in production use at Beech Aircraft Corp. and Hunting Aircraft. Boeing reports that microscopic examination has shown wheat starch blasting to be smoother and less damaging to fibers compared to hand sanding.
Starch blasting leaves a smooth finish on aluminum, bare or clad, and can strip aluminum skins as thin as 0.016 in. without deformation. The media is soft and forgiving and does not cause crack closure or smearing on aluminum alloys.
Testing at Pauli & Griffin's facility is continuing in a joint United Airlines/Boeing/Douglas program on stripping composite substrates and should be completed this year. An approval for multiple stripping using wheat starch is expected from Boeing in the spring of 1993. Plastic media currently has a single strip approval.