Water Toleration of Urea Formaldehyde Adhesive
The methylol urea compounds referred to earlier are truly, if only slightly water soluble, that is to say, the more solvent (water) that is added, the greater the weight of solute dissolved. On the other hand, the resinous liquids used as adhesives are not true solutions but colloidal dispersion, and although it is possible to produce dispersion that are infinitely compatible with water, the reaction products used as adhesives are not generally of this type.
The extreme case of a resin having infinite compatibility with water at all temperatures is an indication that the resin having infinite compatibility with a high ratio of formaldehyde (and probably smells strongly of it), or that it has been relatively under reacted. More detail info about urea formaldehyde. Urea formaldehyde is a result of reaction between urea (a fertilizer product) and formaldehyde (other name is formalin an agent for preservative and also use as fungicide)
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