ArtResin puts red caps in the bottles to help minimize leaks during shipping. Once you open the bottles, go ahead and remove those red stoppers and throw them away.
How Do I Remove The Red Caps From The ArtResin Bottles?
Always wear gloves when removing the red caps - the bottoms are sticky. 
Here are a few methods we found work best:
If the red stopper doesn't want to pull out easily, you can pry it out by positioning a knife or a spatula under the edge of the cap.
Stubborn caps may need to be pulled out with a pair of needle nose pliers.
Do I Need To Keep The Red Caps After I Open My ArtResin?
Once the red inner caps have been removed, you can throw them out and you don't have to be bothered with them again. Replace them if you wish, but we don't necessarily recommend it: the red caps won't help to reduce oxidation and, if you put the wrong cap back on the bottle, the resin and hardener will catalyze and the cap will get stuck in the bottle.
Please feel free to reach out to the ArtResin Customer Service team with any questions at support@artresin.com.
ArtResin: Made For Artists, By Artists
