Epoxies are too brittle, carpenter glues are too weak. I'd suggest
either the solvent based adhesives or the hot melt set. In the solvent
set you need something with good flow out which will mean fairly high
solvent content and attendent smelly cure period.

Sounds like your brush has a 5x10 pattern. How about an aplicator that
has 5 nozzels, pull the trigger 10 times and you are done. Perhaps 60 to
100 pieces per hour. Preheating the brush to 150 to 200 degrees would
help flowout for either the solvent or hot melt glues.

Power applicators are available, pressure tank, hose, and gun affairs.
Haven't used them lately, can't give you any sources. I'd probably give
your cardboard box supplier a call and ask for some pointers.

Tom Gardner wrote:

I have a situation that I need help with. I have a big bunch (3k) of
brushes that need better tuft retention for a special application. The
brushes are 7" long x 3-1/2" wide and have 50 holes/tufts in them. Each
hole is 1/2" deep x 9/32" dia. and each tuft is 3 flat wires bent 180 deg,
and stapled into the hole with a 18 ga., 1/4" crown x 1/2" leg staple. I am
thinking of injecting glue of some kind into the hole with the wire. These
brushes are already made. If I can inject glue or epoxy into the holes, the
material will have to be able to withstand the brushing action and not
crumble or pop out. I wonder if carpenter's glue would work. I'm looking
for leads for some type of powered dispenser too. My budget needs to be
under a buck apiece including labor.

Apparently, the action of the brush in this application is way different
than normal. They use the brushes in a linear motion that is parallel to
the staples. They use the sides of the flat wire to break spoo up rather
than the face of the flat wire to "sweep" like a normal use. This action
has a tendency to rock the staples out even though the tuft retention is
over 40 pounds pull-out strength. (Where's that Unabtaniun when I need it!)