History of the Horizontal Resin Lines
Historically, the Horizontal Resin Lines preceded the development of the plants equipped with multi-shelf ovens. In fact, when the Resin Treatment was not an integral part of the slab production cycle yet, companies keen to treat their stone with synthetic resins were using so-called “tunnel ovens” for the drying of the stone and hardening of the resin.

In the ‘90s the introduction and diffusion of proper Resin Lines confined the horizontal plants to a very narrow niche market consisting of companies specialized in the restoration of broken slabs or dealing in honed-and-filled travertine.

Nowadays, however, it still happens to meet stone processors operating tunnel ovens, especially in technologically backward regions. An exception is represented by the radio frequency ovens which despite configured horizontally are definitely not obsolete systems.

Workings of the Horizontal Resin Lines
Generally, the defining characteristics of the Horizontal Resin Lines are essential design, simple equipment and low level of automation. The typical layout includes a Tilting Bench for slab loading, a 2 or 3 slab-capacity Drying Tunnel, a couple of worktables for mesh attachment or resin application, a Polymerization Tunnel containing 3 to 5 slabs and another Tilting Bench for slab unloading.

The considerably high mechanical speed of the plants should be adjusted according to the properties of the resin applied to the stone specified by the manufacturer (viscosity, hardening temperature and hardening time). Modern Horizontal Resin Lines can easily process 30 slabs per hour indeed, and hence it is necessary to make sure that the drying and resin polymerization times are large enough.

When talking about plants equipped with radio frequency polymerization ovens and treatments with fast curing resins, it is realistic to expect to produce 30 slabs per hour or even more. Nevertheless, it is important to note that the resins which are compatible with radio frequency ovens can yellow or darken and so adversely affect light-coloured stone.

It is also worth bearing in mind that microwave and macrowave ovens are unsuitable for the treatment of onyx, some types of quartzite and materials which present deep hairline fractures, because of their excessively high internal temperatures (60 to 80 C° depending on the model) that may cause onyx and quartzite slabs to break and resin to harden too quickly to get into fine narrow faults.

Concluding remarks on the Horizontal Resin Lines
Having been manufacturing Horizontal Resin Lines for over two decades, we know the subject well enough to express our views on their utility. Horizontal ovens are suitable for the treatment of a small group of materials, regardless of their heating source (natural gas, electricity, infrared, microwave or macrowave).

A horizontal line can be an acceptable solution to fill travertine slabs with polyester resin, although polyester resins tend to yellow and this can spoil the appearance of light-coloured travertine like the renowned “Navona” or “Roman Classico” types.

Horizontal Resin Lines are a good means to reconstruct shattered slabs, which once repaired have to be honed and then coated with coloured resin.

Compact granite slabs with small superficial imperfections can be enhanced through the application of quick setting epoxy resin and polished as soon as they leave the Polymerization Tunnel.

The latest Horizontal Resin Lines from S.E.I.
S.E.I. offers a wide range of solutions to meet the needs and expectations of everyone interested in a Horizontal Resin Line. Thanks to their modular design, all plants can be tailored to each individual factory situation and integrated into an existing automated production line.

For example, an S.E.I. Horizontal Resin Line can be connected to a polishing machine, to resin coat and polish the slabs without breaks. An even more comprehensive combination and the ideal solution for companies with a non-stop production cycle, is to link a honing machine, a multi-shelf oven for the drying of the just honed slabs, a couple of tables for the application of fast curing resin, a polymerization tunnel and a polishing machine.