When i seal, i use a penetrating sealer. Easier to work with, and you dont get any of the problems associated with surface sealers like Resibloc..
Ive been testing out a water based penetrating sealer lately on some spare blocks, seems to be a decent product, but way overpriced (though im only using the free sample) will probably by some waterbased stuff from another company if i ever get some decent sized sealing jobs.
Have a look for ''water based penetrating sealers''
Takes a while to dry though, so make sure you have some good weather..