Goldilocks and the 2 Thinners


This is the skinny on Napco 320 Thinners and All Purpose Thinners, and how to find the Goldilocks combination so your finish is just right.

Always adjust the ratio of Thinners to slow or speed up the flash and dry times of the 320 PolyGlass Coatings.

We supply 2 different Napco Thinners –

  1. All Purpose Thinners (red label)
  2. 320 Thinners (blue label)


When your too hot:

The All Purpose Thinners is great for everything especially when you need a nice flow to achieve that high gloss finish.

By design, it achieves a medium speed in normal conditions 25°c and 75% humidity – for your common applications. This makes doing large areas easier and can compensate for hotter weather.

Hot Tip – If you find you are getting a grainy test pattern or dry finish, try increasing the thinners ration in the PolyGlass mix. You can adjust the ratio up to 1.5, making the mix 2 Resin: 1 Catalyst : 1.5 Thinners. Or 8oz Resin: 4oz Catalyst: 6oz Thinners.


When your too Cold:

As we move into winter and cooler temperatures we may find the All Purpose Thinners a little too slow.

This is where the 320 Thinners will be your best choice. With a faster flash off and dry time you may find this a real help in the cold weather.

Cold Tip – If the 320 Thinners is too quick, you can always blend it with the All Purpose Thinners in 50:50 ratio or whatever works for you. You can also add additional 320 Thinners, up to twice the normal ratio for the 320 PolyGlass Resin to the mix. So 2 Resin: 1 Catalyst : 2 320 Thinners Or 8oz Resin: 4oz Catalyst : 8oz 320 Thinners

I have added a new Work Flowchart called “320 PolyGlass Thinners mixing options” for your reference.

Not too fast, not too slow, when choosing your Thinners, make it just right! 😉