04-21-2017, 03:24 PM Re: My experience spraying finishes. by yuri (After long, I mean L...)
(04-21-2017, 02:24 PM)yuri Wrote: I got ford #4 cup. Any resources I cold read through how to use it? Well, how to measure is pretty straightforward, but understanding what needle/nozzle combination to use depending on measured viscosity to use is not obvious.
The manual for my HVLP rig has a chart that gives starting points (key thing is starting points!) for #4 cup time and N/N combinations.
I think you mentioned having a Qualspray gun? That should have a similar table or Jeff Jewitt should have one on his website somewhere.
So from memory, the numbers may not be correct, if a quick test of my finish shows 35 seconds out of the #4 cup I go to my chart and it suggests that the 1.3mm N/N set is good for 30-50 sec then that's what I'll start with. If I was close to 50, I'd probably thin just a touch rather than move to a larger N/N size. I don't get hung up on the test temperature except that colder == slower and hotter == faster flow from the cup. But if the temperature is comfortable for me, it is probably comfortable for the finish formulation and things will be good enough.
And you may have already noticed that not every finish manufacturer gives viscosity in relation to the #4 cup. There are conversion charts around for the different methods. Google can cough them up pretty easily.
Don't sweat the petty things and don't pet the sweaty things. -- G. Carlin