Getting the Most from Power-Sander Blocks
Foamed-glass blocks change how a power sander behaves: they cut faster than paper, never clog, and keep cutting at the same rate until they are used up. That consistency rewards a slightly different technique than sandpaper habits teach.
Mounting and First Contact
- Seat the block fully on the sander's pad before starting - an unevenly mounted block vibrates and wears one edge.
- Start the sander before touching the work, and bring it down flat. Tipping in on an edge gouges, because glass foam cuts more aggressively than the paper you are used to.
- Let the machine's weight do it. Pressing harder does not strip faster - it just heats the work, loads the motor and wears the block. This is the power version of the family's universal rule: let the block do the work.
Keep It Moving
Because the block does not dull, it will happily dig a hollow if parked in one spot. Keep the sander moving in long, overlapping passes with the grain on wood, and in slow circles on metal. On paint, work until the color breaks to substrate across the whole pass area, then move on - resist the urge to chase the last flecks one spot at a time; the next pass catches them.
Grit Progression
Treat the block range like sandpaper grits: extra-coarse or coarse to strip and level, medium to refine, fine to finish. Stripping straight to bare wood with coarse foam leaves a toothy surface - perfect for primer, too rough for stain. For furniture-grade finishes, end with fine block or a finishing paper pass.
Dust and Lead Sense
Blocks throw less airborne dust than paper - the debris is denser and falls faster - but stripping always makes dust. Ventilate, use the sander's dust port where possible, and wear a respirator for extended sessions. On pre-1978 paint, stop and test for lead first: the EPA RRP lead-safe rules govern any sanding of lead paint, by any method.
Block Life
A block is done when it is too thin to seat safely on the pad - typically after replacing a tall stack of sandpaper sheets. Worn blocks still have a second life as hand blocks for corners and touch-up; see the hand block technique page. For the product range itself, return to the power-sander block overview or read refinishers' field reports.