I'm fairly certain this isn't com[arable, but I use HF filters and they are labeled "60-70 mesh". But if you're thinning to strain it, the filter is too tight. Worse, water borne finishes have a limit to how much they can be thinned (generally it's like a 10% number) so it's possible you messed with the chemistry.

 

I've only ever tried a kitchen sieve with basically a window screen sized mesh. I have an assortment of finish strainers up to 250 micron, but I would not even consider using them as water based poly is just too viscous. The kitchen sieve worked fine and caught all the "strings" that seem to enjoy growing in this stuff 8^)

 

Think of panty-hose material. It's the ideal mesh for water-based paints. This was the suggestion of Jeff (forget his last name) who was the developer of the Enduro line of water-based paints. He subsequently sold his business to General Finishes.

When I was doing a lot of finishing, I bought shoe liners in a box of 100. This is what the Enduro paint company did. These are small shapeless nylon socks that are used in women's shoe stores when a customer wanted to try on shoes. They have an elastic band that was ideal for putting over the top of a one-liter pressure can. And the filtering was perfect for that paint…but I have no idea what the mesh size is.

After years of this process, I migrated over to the 3M PPS system has an integral filter in the lid of the 1-liter cup, so I don't filter anymore. Love the 3M PPS because you can spray in any direction, and, of course, I don't need to buy other filters. I note that the 3M system I use is marked as a legacy, so there is probably a newer version.

 

FWIW - I was taught you want strainer/filter to be no larger than 1/4-1/3 size of spray tip to prevent clogs when spraying.
For 1.3mm tip, strainer of up to ~400um or ~40 mesh would be OK.
The medium 60-70 mesh paper filters sold by HF are ~210-250um. The fine 110-120 mesh are ~140um. The don't carry a course 40 mesh filter, which is largest I have seen and only find at automotive paint shop.

There are many mesh/micron tables available on WWW if need help finding right size.
https://www.directmaterial.com/blog/wp-content/uploads/2014/10/Mesh_v_Micron.jpg
https://www.kmcoating.com/blog/wp-content/uploads/2016/05/mesh-micron-paintspray-filter.png

YMMV

 

The product I'm spraying is Varethane WB poly. I will not even go through a 190 strainer.

It will spray undiluted through a 1.3mm tip. Is this advisable or should I do a nominal 10% thinning anyway?

I was doing just fine thinned, but yesterday I sprayed another piece un-thinned and was not happy to see orange peel. The humidity was also much higher.