Abstract: Substrata for soil-free cultivation are characterized by a relatively low by-volume mass. They are also constituted of fine fibers. The substrata present the advantage of a high degree of water retention, even for small thicknesses.

Abstract: A vitreous product which can be used in agriculture is disclosed. With the exception of nitrogen, this vetreous product contains all the major and minor mineral elements which are essential for the nutrition of plants.The vitreous products can contain the following constituents, taken in the following proportions by weight:______________________________________ SiO.sub.2 25 to 65% Fe.sub.2 O.sub.3 1 to 15% P.sub.2 O.sub.5 1 to 15% B.sub.2 O.sub.3 0.01 to 2% K.sub.2 O 5 to 35% MnO 0.01 to 3% CaO 11 to 35% ZnO 0.01 to 3% MgO 1 to 10% CuO 0.01 to 2% SO.sub.3 0.01 to 1% MoO.sub.3 0.01 to 3% Na.sub.2 O 0 to 2% A1.sub.2 O.sub.

Abstract: Substrata for soil-free cultivation are characterized by a relatively low by-volume mass. They are also constituted of fine fibers. The substrata present the advantage of a high degree of water retention, even for small thicknesses.

Abstract: A liquid mixture containing a heat-expandable resin and a catalyst is cast onto a lower facing, which is heated from below to cause expansion of the mixture and hardening of its lower part. The upper surface of the expanding mixture is covered with an upper facing applied while that portion is still soft, and the composite formed thereby is introduced to a heated enclosure while the upper part remains soft. The thickness of the formed composite, and panels derived thereof, is calibrated or limited by opposed conveyors within said thermal enclosure, which limits the maximum expansion to a value less than the theoretical potential expansion of the foam, allowing hardening to be completed, and subsequent cutting of the composite into panels.

Abstract: An etherified melamine-formaldehyde resin is disclosed that has prolonged shelf life, comparatively low free formaldehyde content, and is especially adapted as a binder for glass fiber mats. The melamine-formaldehyde resin is prepared in several distinct stages including condensation in a basic aqueous solution, etherification by cooling and acidification, neutralization with triethanolamine, and final stabilization. The free formaldehyde content of the resin so produced can be adjusted by reacting it with urea.