Oil Paint Tube

I discovered that opened tubes of paint don't last forever. Adding medium wasn't helping me get a smooth consistency. I came to the conclusion I had to replace those paint tubes that just weren't working.

Here's a  tip from a Utrecht Art Supplies "Ask the Experts" representative :
"You can reduce the chance of paint drying in the tube by keeping caps and tube threads clean so containers can be tightly resealed. Avoid leaving air space in the tube by squeezing paint to the spout top before capping. A small amount of essential oil of clove can be dabbed inside caps to reduce skinning, but this should not be introduced on the palette or colors may be very slow to dry."