I usually spray water-based poly’s as a finish coat on my pieces and find that I frequently need to dilute to get proper viscosity. I’m told that any more than about 15% dilution (with distilled water) will unfavorably change the chemical characteristics of the poly.
Any experience you can share in finding a suitable dilution agent for water-based poly is greatly appreciated.
Jim
Replies
You should not thin waterborne finishes any more than stated on the label. If the label doesn't offer any info, do not thin until you contact the manufacturer.
Water in waterborne finishes is there to act as a carrier of the chemicals that form the finish. It keeps them apart. When the water evaporates, it lets the chemicals come into contact with each other and they begin to react (coelesce) together forming a finish. If you add water, you risk causing too much separation between the chemicals so that they do not come into contact properly or at all. The finish will seem to dry but no real protective film results.
If you want to spray waterbornes buy a waterborne product made for spraying. Do not use a waterborne designed for brushing. Also, use the correct needle and pressure to spray the finish unthinned.
I agree with Howard on this. If you find you need to dilute more than recommended, maybe you need to look at the sprayer you're using - is it the right nozzle?
DR
Thanks much guys for the info. I'll change nozzles but it sounds like the real answer is for me to start paying a bit more money and buying professional grade waterbornes that are formulated for spraying.
Thanks again.
JM
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