Adding on to Lucianno's reply here in the USA we generally refer to the pliers he is refering to as "Channel Locks" which is actually a manufacter. In the shop we may call them "Channies" at least here in the midwest. These are "real" tools which could easily break a Tamiya jar. They are available from many differnt brands and sizes.

With Tamiya jars I will often turn them upside down and squirt a little alcohol or Windex into the cap and let it sit for a few minutes. This softens the paint allowing you to open the top easier. A wise modeler wipes the top of their jars before recapping but I don't.

I TRY TO WIPE THE JARS BUT I forget ALOT .Yes the real name is slip lock pliers . In the east we just called them channels. I have them from 18 inches down to 3 inches lol was in the HVAC business 35 years. however I've broke more bottles or at least stripped the labels off lol , Im used to bull work I guess. the Gunze is nice and easy . ( arthritic hands ) need all the help I can get lol Thanks guys !

Adding on to Lucianno's reply here in the USA we generally refer to the pliers he is refering to as "Channel Locks" which is actually a manufacter. In the shop we may call them "Channies" at least here in the midwest. These are "real" tools which could easily break a Tamiya jar. They are available from many differnt brands and sizes.

With Tamiya jars I will often turn them upside down and squirt a little alcohol or Windex into the cap and let it sit for a few minutes. This softens the paint allowing you to open the top easier. A wise modeler wipes the top of their jars before recapping but I don't.

Here's a low tech solution- wrap a thick elastic band around the lid. It works quite well for opening stuck caps.

One other thing you can do that works to open a bottle if it's really stuck-- turn it upside down on your workbench, using a larger paintbrush or pipette, dribble a little lacquer thinner around the stuck rim of the cap. Within a minute or two, wipe off the cap, turn the bottle over and voila! It'll twist right off. It'll go like "greased lightning" if you use the "rubber band method" above.
VR, Russ

One other thing you can do that works to open a bottle if it's really stuck-- turn it upside down on your workbench, using a larger paintbrush or pipette, dribble a little lacquer thinner around the stuck rim of the cap. Within a minute or two, wipe off the cap, turn the bottle over and voila! It'll twist right off. It'll go like "greased lightning" if you use the "rubber band method" above.
VR, Russ

Not for everyone but if needed I use a small strap wrench to hold the bottle and channel locks on the cap.

Back in the day I was trying to get one of those old square Testors paint bottles open and nothing would work. So I got two pairs of pliers one to hold the bottle and one to hold the cap. That cap was stuck. I gave it a twist and broke the bottle in half. Was not amused as the mess got me in trouble with Ma.

The secret to tamiya and gunze bottles is to never shake them, only stir (known as the reverse James Bond). That way no paint gets on the threads and they open easy every time.

That works with metal caps on glass bottles by differential thermal expansion; the metal expands considerably more than the glass. I doubt that it would work for plastic - certainly not by the same mechanism!

Hot water and my hands,always work,but i try to keep the treads clean,for the Humbrol "kids safety lid" i simply cut the safety off becose actually are "Human safety lid"....