March '23

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G R A P H I C S - P R O. C O M M A R C H 2 0 2 3 • G R A P H I C S P R O 7 1 Contamination is is a problem for various reasons, with the most obvious being that any- thing in your abrasive will clog up your blaster. e least serious concern is some- thing lodging itself in your nozzle, pre- venting you from blasting. This is an easy fix if you catch onto this being the problem. A much more serious issue is getting contamination into your blaster. Some of us who engage in multi-stage blast- ing often use peel resist in the cabinet to eliminate the task of taking the object to be blasted out of the cabinet and putting it back in after every stage. At times, a small resist piece escapes into the hopper of the cabinet and can get through the screen and into the pressure pot. If that happens often enough, you end up with an obstruction in your pot which will ulti- mately prevent the abrasive from flowing, and you end up having to take the pres- sure pot apart. Contamination is also a problem if you are in the habit of blasting a variety of sub- strates with the same abrasive: one day you blast wood, then stone, then glass (which is not recommended). Residue of stone or wood particles within the abrasive will be a problem if you then blast on glass. ese particles may "eat through" photo resists and chip the glass. If you have an attached Type of abrasive Etching speed Number of cycles Brown sand Medium slow 2 White crystal silica sand Medium slow 2 Garnet Medium 4-8 Aluminum oxide Medium fast 60-80 Silicon carbide Fast 80-100 One version of a free-standing reclaimer that can be retrofitted onto any blasting system. If you have a good blast cabinet or blast room in which to etch, you can use any of the abrasives that can be recycled. (Image courtesy Ruth Dobbins) pressure pot, there is a screen built into the system that covers the entry port of the abra- sive into the pressure pot. Make sure you check that screen once in a while, as it can be damaged during cleaning of the inside of the cabinet, and then any contaminant can fall straight into the pot. If you have a free-standing pressure pot, you must always screen your abrasive while refilling. GP Cost Effectiveness of Abrasives The biggest challenge for all of us is to keep our abrasive dry and uncontaminated.

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