Re-finishing checkered handgun grips

[AzRednek]

Any suggestions on refinishing handgun grips on keeping the poly from building up in the checkering?? I had a dismal failure years ago spraying the poly  The poly builds up in the checkering way to thick and looks sloppy. After stripping the new finish off I tried it again using tape over the checkering. Some of the poly got in under the tape and looked like sh!t. I’m going to attempt it again using finger dunks instead of spray but want to avoid getting any into the checkering. My game plan is to thin the poly with paint thinner and just lightly coat the checkering. 
 

Im looking for suggestions on how to keep the poly out of the checkering while covering the rest of the wood. I thought about using molding clay in the checkering then washing it out with soap, water and a soft brush after the finish hardens. I had good luck in the past washing out the sticky soft clay when I used it as a dam preventing glass bedding from working its way into a rifle stock’s barrel channel. 
 

Any suggestions or even speculation is welcome. 

[AzRednek]

On 7/20/2020 at 3:52 AM, The Zen Master said:

Can you spray the poly and after it is all good and dry ( a few days) then clean the checkering with a checkering file?

That’s probably the best way but my only checkering tool doesn’t match up, way to thick. I’m to lazy to do it right and when I attempted to buy some clay today. The arts and craft store closed permanently.
 

Guess I’ll have to wait for the clay next time I weave in and out of the weirdos, illegals and the other ethnic group that that own the joint by blocking aisles, push their way to the front of the checkout lanes and park in handicapped spots at Wally’s. My last visit to Wally’s I watched two minority children each eat a banana then as mom watched they dumped the peels on the shelf in the bread aisle. My X was right should’ve moved up north feeling more and more like I’m living in the ghetto. 

[Dr.Hess]

Is there a Hobby Lobby near?  I think that's where I got some clay.

[AzRednek]

15 hours ago, The Zen Master said:

Or the nearest Michael's?

I think there is a Michael’s nearby just west of I-17 on Peoria. I have to make a trip to that strip mall for dog food in the next few days I’ll check it out. 

Doc there is/was a Hobby Lobby here but it’s not connected to the corporation. It was independently owned but after the owner died I’m not sure if it’s still around. It was a great place in my early teen years. They had a terrific slot car track and even had a nickel drag strip. When I was about 12 I traded Indian Head pennies there for slot cars and accessories. Way back then I got $35.00 in store credit for a slightly shiny either 1908-S or 1909-S Indian Head penny but I had to split it with my younger brother.