This review summarizes recent developments in foam forming that were mainly carried out in pilot scale.In addition to improving the efficiency of existing processes and allowing better uniformity in material,a wide variety of raw materials can be used in foam forming.The focus of this review is thin webs-papers,boards,and foam-laid nonwovens,along with the pilot scale results obtained at VTT in Finland.For paper and board grades,the most direct advantage of foam forming is the potential to produce very uniform webs from longer and coarser fibers and obtain material savings through that.Another main point is increased solids content after a wet press,which may lead to significant energy savings in thermal drying.Finally,the potential to introduce”difficult”raw materials like long synthetic or manmade fibers into a papermaking process enables the manufacturing of novel products in an existing production line.
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