The short answer is to add creamed honey to your liquid honey and it will serve as seed crystals and converting all of it to creamed honey. If you don’t already have some creamed honey you can take crystallized honey and grind it up into the smallest crystals possible. Either way you get your seed honey you need to mix it thoroughly with the rest of the honey and store it in a cool place.
I accidentally made it one year when I harvested honey from a hive that didn’t make it through the winter. There must have been some crystallized honey in it as it turned into something as smooth as butter and tasted amazing. Unfortunately it’s now all gone.
A Prof. Dyce from the University of Cornell did research on this to produce a more controlled process and his write-up can be found here.
Give it a try, if you don’t like the results you can always warm the honey back up enough to melt the crystals.
First of all let me make it very clear that crystallization of honey is natural and except for those rare honeys that do not crystallize (like acacia) honey not crystallizing, or taking a very long time to crystallize is actually an indication that your honey may not be 100% honey or it filtered to such a high degree that much of the good stuff that we want in natural honey is gone.
For most things I actually prefer crystallized honey. Keeping it in a wide mouth mason jar means I can just spoon out what I want and it doesn’t run all over the place. In fact I add crystallized honey to the stuff that hasn’t crystallized yet to seed the crystals into growing sooner. My favorite is something called spun or creamed honey. The crystals are very small and produces something that is smooth and spreadable like butter.
However if you want your honey liquid all you have to do is warm it up. Keep in mind if you get it too warm you destroy some of the components that make local raw honey so good for you. If you keep your honey in glass jars it is easier to warm it up if you feel it is needed. Just heat up some water (or if your tap water is hot enough just use that) and put the jar in that.