Gummed rolling papers carry an adhesive component applied as a narrow strip along one edge of the leaf. NOVEX’s gummed products use natural gum arabic for this purpose. In this article, we summarise from a technical perspective what gum arabic is, how it is applied during production and which parameters matter for quality control.
What is gum arabic?
Gum arabic is an exudate that seeps naturally from the trunks and branches of acacia trees (mainly the Acacia senegal and Acacia seyal species) and hardens on contact with air. The hardened pieces are collected, sorted and prepared for industrial use as granules, powder or solution through various processing methods.
Chemically, gum arabic has a complex structure consisting mainly of polysaccharides with a small proportion of protein. Its most relevant technical properties are:
- It dissolves readily in water and forms solutions of relatively low viscosity.
- When dry, it forms a thin, flexible film.
- It is not tacky when dry; it becomes adhesive on contact with moisture.
These properties make gum arabic well suited as an adhesive component that is applied in a narrow strip on thin papers and only functions once moistened.
Its function in rolling paper
The gum strip runs along one of the long edges of the leaf and allows the edges of the paper to be secured to each other. The width, position and continuity of the strip along the leaf must match the format. The strip must be fully dried so that it does not cause leaves to stick together inside the booklet.
Application in production
On Interleaving Booklet lines, the gum strip is applied in-line as the paper is fed from the reel, before the folding and interleaving steps. In broad terms, the process can be considered in three stages.
Solution preparation
Gum arabic is dissolved in water at a defined ratio to prepare the application solution. The concentration and viscosity of the solution are adjusted to suit the application system and line speed. Where necessary, the solution is filtered so that undissolved particles do not affect strip quality.
Strip application
The prepared solution is transferred as a narrow strip onto the paper travelling along the line, in a position that corresponds to the edge of the leaf. The width of the strip and its distance from the paper edge are determined by the format dimensions. The balance between line speed and application quantity is decisive in achieving a uniform, continuous strip.
Drying
The applied strip is dried before the folding and interleaving steps. Insufficient drying can cause leaves to stick together inside the booklet, while excessive drying can deform the paper. Drying conditions are therefore assessed together with line speed and ambient conditions.
Quality control parameters
For gummed products, quality control covers both the raw material and the production stages. The main parameters generally monitored in the industry are:
- Appearance, colour and foreign matter checks at raw material acceptance
- Concentration and viscosity of the solution
- Strip width and position relative to the leaf edge
- Continuity and uniformity of the strip along the leaf
- Degree of drying and absence of sticking between leaves
- Protection of the finished product against ambient humidity during storage
Raw material acceptance
As gum arabic is a raw material of natural origin, properties such as colour, solubility and viscosity can vary depending on the tree species, the region where it is collected and the harvest period. Raw material acceptance is therefore carried out batch by batch. The product specification and analysis documents provided by the supplier are assessed together with the results of the acceptance checks. Deviations between batches are balanced through concentration and viscosity adjustments at the solution preparation stage.
Storage conditions
Because gum arabic interacts with moisture, both the raw material and finished products need to be stored in dry environments at suitable temperatures. The moisture barrier of the packaging and the carton layout are also assessed from this perspective.
Gummed and ungummed products
Rolling papers can be produced with or without a gum strip. For ungummed products, the solution preparation, strip application and drying steps are not part of the production flow; the other steps continue in the same way. The product specification must therefore state clearly whether a gum strip is to be included. For gummed products, the alignment of the strip position with the format is also one of the main points checked at the sampling stage.
This article is provided for technical information only. The word “natural” describes only the origin of the raw material; it does not imply any health attribute or claim of superiority.
For information on gummed and ungummed product options, see the Products page; for our quality processes, see the Quality & Compliance page.
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