Originally Posted by
prairiepedaler
Easy does it fella. There was no "question", an observational statement was made. As per the OP, the viscosity is different between the two "identical" products. I remember this difference clearly from using the older stuff from long ago. The older stuff had different viscosity even when it was purchased new.
In as clear a wording as I can make it: the new stuff doesn't last as long compared to the old. It's been thinned down. So, if there is some NOS old Tri-Flow bottles on a shelf somewhere, buy them, but only if good Tri-Flow is your thing.
Are you comparing the viscosity between a 20 year old product and a new product? Or have you measured the viscosity 20 years ago and have measured it now?
In the previous case, 20 years of sitting on a shelf in a polyethylene bottle
will result in solvent loss. The bottle isn’t imperious to the amyl acetate and merely opening and closing the bottle will result in some solvent loss. Additionally, what if you left the bottle uncapped at some point? All these factors would result in solvent loss and increased viscosity.
If the latter is the case, why would you even measure the viscosity 20 years ago and now? Even if you did measure the viscosity are you sure that you have measured it the same way 20 years ago and now. Viscometry has changed somewhat over the intervening years and could result in measurement errors when comparing products with that large a age gap.
I’d suspect the former, however.