Mumbles Posted November 8 Posted November 8 If you're looking for PVB, try searching for the brand name Butvar. Talas online sells it, but it's a lot pricier than I remember it being. https://www.talasonline.com/Butvar-Resin As an aside, they have some of the nicest wheat paste I've ever used. It used to cost about 2-3x of what Playbox or other cheaper brands were running, but they look to have dropped the price on 5+lb bags to a much more attractive price. I've had nothing but problems with shellac and alcohol. I haven't heard of a lot of issues with phenolic resin and alcohol binding, but it's also not unreasonable. I suspect a lot of people are using 91% or 70% IPA for binding, and I wonder if there is anything to it or if the water slows things down enough to prevent skinning over or driving itself in as much. It may seem counterintuitive, but in certain coating industries, slower evaporating additives are used to prevent the coating from getting hazy or remaining tacky. Remaining tacky is generally a sign of incomplete solvent removal, and has the same root cause as what we'd call a skinned over or driven in star. That might be something to consider as well if you're looking for a different direction to fix this issue. On paper, the solvent will take more time to evaporate, but in practice it's overall faster because locking solvent in is prevented. This is just me thinking out loud. There are two main flavors of phenolic resins, Novolac and Resole. We typically use Novolac. It's generally a solid, is acid catalyzed, and can be cross linked with hexamine or other linkers. Resole resin is generally a liquid, is base catalyzed, and can be thermally cross-linked on it's own. I wonder if the base present from the carbonate is somehow interacting or otherwise impacting the acid catalyzed Novolac phenolic resin in some way. 1
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