PVA/PVA
Mixture
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PVA/PVA
Mixture
Polyvinyl acetate (PVA) is the
adhesive used for general work here in our lab. It is a "plastic"
adhesive. It is not reversible (in theory, at least), so if work being
done involves reversibility issues, Japanese tissue, adhered with wheat
paste, is applied directly to the work as a barrier layer. Because PVA is
a liquid of high surface tension, its application meets with
considerable brush drag. Thus, it is not the adhesive of choice for large
surfaces unless board-to-board joints are involved. PVA is used for all
such joints.
PVA mixture is a 50/50 mixture
of PVA and methyl cellulose. It sets a bit more slowly than PVA,
allowing for an extended working time. The methyl cellulose facilitates
application by serving as a surfactant, reducing surface tension and thus
reducing brush drag. For most work, we use mixture rather than straight
PVA because it is easier to manage. Also, for applications other than
board-to-board joints, there is no appreciable difference in bond
strength between straight PVA and mixture.
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