Recycled fibre is cheaper than virgin pulp, but it brings its own baggage – ink, toner, glue and stickies. How well you remove them decides whether your sheet comes out grey and spotty or clean and bright.
How deinking works
Deinking happens in two stages. In the pulper, chemicals loosen ink from the fibre. Then flotation cells or washers carry the detached ink away.
- Deinking agents – such as Sapco DI deinking agent and our wider deinking chemicals range – help ink particles separate and collect at the surface during flotation.
- Alkali and silicate swell the fibres so ink releases more easily.
- Hydrogen peroxide stops the alkali from yellowing the pulp and adds brightness.
- Enzymes can help with toner-heavy office waste.
Benefits of a good deinking programme
- Higher pulp brightness and fewer dirt specks.
- Less need for virgin pulp blended in.
- Fewer stickies reaching the paper machine.
- Better yield – less good fibre lost with the reject.
Use cases
- Newsprint and writing paper from old newspapers and office waste.
- Tissue from recycled white grades.
- Top liners of duplex board.
Practical tips
- Pulp at the right temperature and consistency – deinking chemicals work much better warm.
- Sort the furnish: mixing coloured, coated and laser-printed waste makes ink removal harder.
- Watch water hardness; flotation chemistry depends on it.
- Control stickies separately with stickies control products.
- Control foam in flotation with a suitable pulp mill defoamer.
FAQ
Can deinking replace bleaching?
Not fully. Deinking removes ink; peroxide bleaching lifts brightness. Most mills need both.
Struggling with dirt counts or brightness? Tell us your waste paper mix and target brightness – we will suggest a deinking programme. Talk to us →