except I never can get the full amount of liquid from the boil kettle and usually end up 1/2-3/4 gallon short of what I would have because there is so much loss absorbed in the hops.
Is there anything I can do to prevent this? What about hop bags, anyone have success with those? Will one of those really help get the best utilization?
I do partial Boils (usually 3 gallons) also. Are you adding water? Pellet hops in my experience actually absorb only a cup or so max (this estimate based on the hop/trub sludge I get after straining.)
I use leaf hops in bags most of the time. To reduce the boil off and get better hop utilization, at every "event" I top off the water to 3 gallons, after the hot break I top off, at the 30min hopping I top off and at 15 min add and at flameout. This way I am cooling the full 3 gallons.
If you are using a strainer just use a sanitized spoon and press down on the trub to drain more liquid. I usually pull the hop bags out and use them as a filter to pour the wort thru to the strainer, then crush em with the spoon to wring out as much as possible.
If you are losing 1/2 - 3/4 gallon sounds like it is evaporation/boil off, not absorption by the hops.. even using leaf, I never get more than a cup or two of loss from absorption.
PS when using leaf hops in the bag I found using 2.5 gallon hop schedule for pellets gets me the same result with 3 gallons and leaf that I would with 2.5 gal and pellets.