For the past three months I have been using these for my daily synergy blend of Essential Oils. I had been using the same brand in Single "0"' size filled with straight EO's but decided I needed to go up a size so I could do a 50/50 blend of 8 drops of my EO's with 8 drops of grapeseed oil. So far these capsules haven't dissolved once filled. I do keep them in the refrigerator although I probably wouldn't have to since none of the oils need refrigeration. I do keep them in the filling tray so they stay upright to safeguard against leaking - make sure you hear the cap 'snap' on for good seal. All in all - these work for my needs and I will continue to use them.