The card shows the blob technique on hammered card (the side panel). I picked this photograph as it shows the hammered texture of the card quite well.
Use a large brush and cover the piece of card completely, covering all the white, don't worry about getting perfect lines as you will add blobs of ink randomly all over this initial wash. Don't worry if your wash looks pale, this is good, as it gives a light background to the blobs you add later, giving even more dimension.
Move the card around so the blobs run a little. Dip a detail paint brush into the wet ink on the card and pull out the ink to create little channels so that the wet ink flows into them. You can also make little dots with the paint brush. Play until you are happy with it. If you really want to go to town, you can blow the ink around (gently!) through a straw.
Leave the card to air dry if possible as it will give the ink and mica time to separate on the card. It should dry in about 1/2 hour to one hour depending on how wet it is. If you can't wait that long, leave as long as you can then finish off with a heat gun. I usually make lots of backgrounds with various techniques and leave them drying around the kitchen tops until I run out of room! I then start drying the driest first with a heat gun just to finish them off before making a lovely pile to use later!
If you heat it with your heat gun straightaway it will give an overall shimmery effect, which does make a nice background too, but less dramatic!