Brush restore advice needed

[Yellow Jim]

Just looking for a bit of help regarding one of two brushes I plan on fitting new knots into. I've taken both of the knots out of the two brushes below, I cut the bristles down and drilled the knots out.

When I drilled the knot out of the brush on the right, it turns out the handle is completely hollow inside, any suggestions about what I should fill it with, to build it up to the required height to fix the knot to? It will accept a 20mm knot.

The brush on the left will accept an 18mm knot and shouldn't be a problem as the bottom half of the handle is filled with solid material (some kind of concrete or something similar).

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[henkverhaar]

You could use epoxy, but it would take a 'huge' amount of epoxy. I would suggest looking for a synthetic type putty for the bulk, then top up with epoxy... Or maybe an acrylic resin?

 

[antdad]

Use car body filler like Isopon P38 or similar, should be able to get a tube from Halford's or any car accessory & parts retailer.

You could even use a gap filling adhesive like Gripfill or even a polyurethane based sealant that you can layer if you have an application gun handy.
Not expensive anyway but very useful to have around, you can get water based versions that will be less stinky but I've never used them. Probably fine.

 

[Yellow Jim]

Cheers gents. I've just ordered a pack of this epoxy putty from ebay, should do the trick.

Now I just need to decide on the knots and get them ordered.