Block bottom bags in natron kraft paper – the industry standard for mills & bakeries

Block bottom bags in natron kraft paper – chemically treated, high-strength kraft paper with the classic flour-sack look. Available in multiple plies for heavy powders, in natural brown or bleached white. The industry standard for mills, bakeries and artisan producers for over 100 years.

Further variants in this packaging family: block bottom bags overview, 4-ply block bottom bags and block bottom bags in kraft paper – each with its own specialisation in material, format or application.

Related ranges for other application areas: side gusset sacks, food-grade cross bottom bags and stand-up pouches in kraft paper.

Packaging direct from the importer since 1976 – fast shipping, transparent quantity discounts and free samples before your first order.

Further industrial and food packaging

Further block bottom bag variants

Popular individual products from this range:

Shipping & terms

Shipping from our German warehouse. Natron kraft standard sizes are usually in stock; custom sizes and printing are scheduled individually within the delivery window. No minimum order value. All customers – B2B and B2C alike – receive quantity discounts for pallet quantities. Free samples via our enquiry form.

What are natron kraft block bottom bags?

Natron kraft is a special grade of kraft paper produced by the sulphate process using caustic soda. Compared with standard kraft paper it has considerably higher strength, a finer fibre structure and better printability. These very properties have made it the industry standard for flour sacks, animal feed sacks and all applications under high mechanical load.

Block bottom bags in natron kraft paper combine this high-strength quality with the rectangular, free-standing block bottom form. For mills, bakeries and food producers this is the proven packaging format: flour, baking mixes, sugar and heavy powder granulates find a stable pack here that does not tear even at a 5–10 kg fill volume. The natural brown look of the natron kraft paper signals traditional craftsmanship and authenticity.

Our natron kraft block bottom bags range is available in multi-ply versions (typically 2- to 4-ply) for high strength, with or without a PE inner coating for moisture protection, with or without a valve for machine filling. Fill sizes range from 500 g (consumer flour) to 25 kg (industry standard). Printing in letterpress or flexographic printing with brand designs is standard, as is the natural brown look for an authentic artisan appearance.

What are natron kraft block bottom bags suitable for?

  • Mills & flour industry: the classic choice for flour, baking mixes, durum wheat semolina
  • Bakeries & baking businesses: baking mixes, speciality flours, baking ingredients in catering packs
  • Animal feed & feedstuffs: dry feed and granulate feed in 5–25 kg packs
  • Fertiliser & substrates: garden and agricultural powders with high strength requirements
  • Industrial powders & chemicals: construction chemicals, cleaning powders, industrial granulates
  • Artisan packaging: authentic flour and baking-mix look for direct marketing

Which natron kraft variant is the right one?

  • 2-ply: light powders (flour 1–2 kg), consumer packaging
  • 3-ply: standard industrial packs, animal feed 5–10 kg
  • 4-ply: heavy granulates, industrial powders in 10–25 kg
  • Natural brown: classic flour-sack look, traditional, cost-effective
  • Bleached white: premium look, a little more refined, better printability
  • With PE inner coating: moisture protection for sensitive powders
  • Pure natron kraft inner: breathable for flour and seed
  • With or without a valve: valve for machine filling, without for manual closing

Your benefits with natron kraft bags from Elke Plastic

We have been importing industrial packaging bags directly from the manufacturer since 1976. For natron kraft block bottom bags, the paper quality is decisive: inferior natron kraft paper leads to tears when lifting heavy sacks and to complaints during shipping. Our suppliers meet the strict requirements for consistent tear resistance and uniform layer thickness – so that even at pallet quantities the quality remains stable across the entire batch.

Our packaging specialists advise on ply configuration and inner finish: for flour at risk of clumping, valve sacks are ideal because they release the air in a controlled way. For seed, a breathable inner layer is essential. For moisture-sensitive powders, a PE inner coating is needed. So you don't get a standard sack, but the optimum configuration for your production line.

Shipping is from our German warehouse. Natron kraft standard sizes are usually in stock; custom sizes and printing are scheduled accordingly. Private customers and hobby millers order standard quantities. All customers – B2B and B2C alike – receive quantity discounts for pallet quantities. Free samples are of course available on request.

Frequently asked questions about natron kraft block bottom bags

What distinguishes natron kraft paper from standard kraft paper?

Natron kraft paper is produced by the sulphate process using caustic soda, giving it a finer fibre structure and higher strength. It prints better and is more resistant to tearing. Standard kraft paper is cheaper but less suitable for heavy loads. For classic flour and animal feed sacks, natron kraft paper is the industry standard.

How many plies do I need?

For 1–2 kg of flour, 2-ply is sufficient. For standard 5–10 kg packs, 3-ply. For heavy granulates of 10–25 kg, 4-ply or more. The multi-ply construction distributes the mechanical load and prevents tearing.

With or without a PE inner coating?

With a PE inner coating: moisture-tight, ideal for moisture-sensitive powders (white flour, baking powder). Without a PE inner layer: breathable, ideal for flour, seed and some foods that would otherwise be prone to mould.

Are the sacks food-grade?

Yes, available for food contact. The inner ply must be food-grade certified – either an unsized natron inner layer or a food-grade PE inner layer. We supply declarations of conformity on request.

What is a valve sack?

Valve sacks have a small opening in the base with a non-return flap. During machine filling, the displaced air escapes and the valve closes automatically. For flour and powder granulate in industry, valve filling is the most efficient technique.

How much can I load them with?

2-ply: up to 5 kg. 3-ply: up to 15 kg. 4-ply: up to 25 kg. For higher loads there are 5- or 6-ply special versions. The base construction (glued, sized, sewn) further influences the load capacity.

Are the sacks weatherproof?

Pure natron kraft paper is NOT waterproof – in heavy rain it softens and loses its strength. With a PE inner or outer coating they are splash-proof. For outdoor storage we recommend a PE outer layer or an additional film overwrap.

Can the sacks be printed?

Yes, natron kraft paper prints very well in letterpress or flexographic printing. For 1–2 colour brand designs, letterpress is economical; for elaborate multi-colour prints, flexographic printing. The run size determines the printing method.

Are they recyclable?

Pure natron kraft paper is fully recyclable in the waste paper stream. With a PE inner coating they are only partly recyclable – separation in the recycling process is complex. For full recyclability we recommend variants without a PE coating.

How does natron kraft differ from classic kraft paper?

Natron kraft paper (sulphate paper) has longer, finer fibres, higher tear resistance and a smoother surface. Classic kraft paper (sulphite paper) is cheaper but has lower tear resistance. For industrial applications under high load, natron kraft paper is preferable.

Are smaller runs possible?

Stock items in standard sizes are available from stock. Custom printing becomes worthwhile from larger runs – artisan producers often start with standard stock plus labels and switch to their own print later.