The blanks I've always built up, have been sealed off on the smaller diameter sides, with pressed-in black rubber. You guys in the States call in RTV Rubber.
The Sage Z-Axis blanks don't have them, so both ends of each blank piece is open, you have to seal it yourself.

I cannot find RTV rubber, in South Africa the hardware stores don't know it, and don't understand what I am looking for.

Two questions:
1. What do you guys use? I've tried foam rod-grip material, but it's a little too stiff, but does work. You just put a little epoxy on it. Tricky to cut it to size and get a nice round "ferrule" to slide into the blank. I've also used Car Silicone Sealer, black. It can handle extreme heat/cold conditions, but I was always weary of it coming out.

2. Why bother with this?? It serves no function. I like it though, it makes the blank sections look "finished".

I called a well known rod builder here in S.A., he told me he just puts 5-minute epoxy in there. I don't agree with this, plus it's clear....so looks tatty I reckon.

What else can I use? Or suggestions?

It does serve a purpose. When a blank is flexed it goes out of round a bit. At the ends, this can lead to cracks over time and repeated use. So something is usually put in there to prevent this sort of thing. You don't worry about it on the very butt of the blank because that area doesn't really get flexed. But the open male end of a ferrule is different - it is heavily flexed.

You can use thin wall brass tubing to punch perfect rounds out of EVA foam. Insert from the butt of the blank.

RodBond works well for this.

ATV rubber is often referred to as silicone gasket material. Comes in a tube.

............

You could paint the 5min epoxy flat black as well. Do it while the epoxy is still warm (NOT WET!) and the paint will bond with the epoxy. Testors model car paint.

DR

Tom, thanks for the info! This clears things up for me.

DR, I''m just worried that the 5 min epoxy has no "give", so maybe the gasket material, or EVA grip foam would be better?

Mike

I hold the male ferrule tip against a flat piece of foam and turn it. It will cut out a piece of foam like a cookie cutter that is an exact fit. Then epoxy it in place. Be sure to clean the blank well with alcohol.

Back when I went through the St Croix plant, what they were doing is coloring the epoxy black and filling the ends with it.