To purge or not to purge…

It is a long time since I completed a colour change in a busy mould shop, but I can remember spending large amounts of time, and a lot of polypropylene, becoming increasing frustrated by the tiniest amount of red compound that just would not shift.

I also remember planning boards in the mould shop looking three weeks into the future – perhaps I am wrong but I don’t think that is possible any more.  Even with the very best planning we can’t avoid unplanned tool changes in our efforts to meet customers high expectations.

Machines and people are expensive and can’t be unproductive, so spending unnecessary time purging a bright red nylon out of a machine is not an option – but there is an answer…


Barrel Blitz Universal (BBU) is the world leader in clearing carbon from your equipment. It is a purging compound made up of a stable, easily clearing polymer and Aquapurge’s proprietary Scrubber Concentrate.

Its primary uses are:

  • Colour changes,
  • Material changes,
  • Clearing carbon.

Clearing Carbon – by this we mean fully degraded materials and plate-out from concentrated pigments or additives – can either be done in isolation but more importantly every time you use BBU for colour or material changes.

Build up of carbon or plate-out it is not uniform across the screw; in the majority of cases it starts at the compression zone and gets worse through the metering zone.

This results in a reduction in the depth of the metering zone, which means that you are trying to force the same amount of material from the feed zone through a smaller volume metering zone. This either succeeds or you get a measure of screw slip which results in an extended screw back time.

In either case you get an increase in shear placed on the melt which results in:

  • Increased melt temperature
  • Longer cycle
  • Different flow characteristics through the mould
  • Voids, flash, splash, gassing

Which equals rejects and wasted time……

This causes a reduction in the processing window and extended set-up times as you will have to change conditions from your set-up sheets to get the same quality result, which means less machine utilisation, lower output or higher cost which means less profit.

If your machine stays in the pristine condition as when it was delivered, the culmination of all these small individual savings has a huge effect on machine utilisation and output.

Due to the effectiveness of BBU, Plastribution will often use it when conducting trials on a customer’s site. It seems sensible to us that we start with a clean machine before we start. Often customers will be surprised at the amount of carbon BBU will drag through the barrel.

Not convinced? Try some!

Give us a ring on 01530 560560 and we will send you 5kg and some instructions how to use it. We are pretty sure you will want some more.