Learn to paint in Acrylic paints - Step by Step
I had some Acrylics sitting around here for a few years in this heat and some of them are turning to liquid. I can shake the tube and hear them gurgling around. When I try to put some on a palette I get a consistency of water.
Should I just order some replacements and throw these away?
Have had the same issue myself! Latex house paint needs to be shaken/mixed at the store not only to mix in the pigments added at the time of purchase, but also to evenly re-suspend the various components into the actual fluid base. The solid materials tend to settle out during storage. The same thing happens to our tubes of paint, but it normally takes much longer because the paint is thicker.
Since the fluid is lighter than the paint solids, and more fluid, it comes out of the tube first. When the paint finally emerges, it may still be soft enough to use. If so, you got lucky. If not, you may not even be able to squeeze the paint out of the tube, so using it is not an option. If the paint is still "soft" but on the firm side, you can mix a bit of gloss medium with it and make it easier to use. I would not add water as that would only thin the emulsion that much more and result in a weaker paint film.
The time frames involved in this separation vary quite a bit. I have Liquitex tubes from 20 years ago that are fine, but Grumbacher and W&N colours completely solidified over the same time frame. Some of the oldest Golden tubes I have are about 6 years old with no sign of separation. Since the various manufacturers use different polymers and formulations, there will probably always be differences in shelf life.
If any of the hardened tubes are Cadmium colours, do not just throw them away. Cadmium is a toxic heavy metal and can leach out of landfill sites. Instead, slit open the tube and allow the paint to completely dry, as in rock hard. When all of the acrylic polymers are solid, the pigment will no longer leach from the paint and it can safely be discarded.
Prevention? Not aware of anything one can do with tubes to prevent separation, we cannot manually shake them hard enough to remix the contents. Limit the number of tubes you have on hand by learning to work with a minimal number of colours. Don't buy large tubes or jars of colours you use less frequently. If you find more problems with one brand than another, maybe think about changing brands. When you first notice a colour starting to firm up, consider using it for tonal underpainting; perhaps you can put it to use before it having to toss it out. Squeeze it into a small glass jar (baby food?) and mix it with medium using a stir stick or stiff palette knife. There is quite a range between getting stiff and becoming too solid to salvage, so the most appropriate response might be - "that all depends"!
This got me thinking, because I have never seen anything from a manufacturer on the topic. To that end I just posted the basic question to the Technical Support folks at Golden. Will see what sort of response we get. Doubt they are open on weekends, so it may be a day or two. . .
I wanted to order replacements for the bad tubes. I went downstairs and made out my list and began ordering.
When I finished I went and got a drink of water and came back, ordered the paint and waited for the order to be accepted and shipped.
Then I realized I had turned the tablet over and ordered new watercolor paints.
The paints in question were W&N and Grumbacher. Guess that verifies what was said earlier.