In a hot jar, place 2 bay leaves, 2 garlic cloves, 1 tsp mustard seed and 2 heads of fresh dill or 2 tsp dried dill seed. Pack cucumber slices into hot jar, leaving 2 cm of headspace. Add hot liquid to cover cucumber to within 1 cm of top of jar. Using a spatula, remove air bubbles and adjust headspace, if required, by adding more cucumber slices and hot liquid. Wipe the jar rim clean to remove any food residue. Place lids and bands on jars and screw tight until resistance is met. Do not over tighten. Return the filled jar to the rack in canner and repeat for remaining jars.