Filling cracks in wood

So I am completly new to using Resin and I have a TON to learn.  As I am learning I am working with what I can easily get my hands on.  I am working on woodturning projects and I am basicly using firewood.  there are lots of small cracks and imperfections I need to fill with epoxy.  I got Amazing Clear Cast to start with because it was reccomended and seemed prety easy to begin with.  The problem I am having is it is not filling all the cracks in the wood.  So my question is do I need to use a presure pot, or is there a product that is not as thick while it is cureing that will fill the voids better?  or am I even asking the right questions?  I would love to hear any suggestions you all have.