I don't know how heavy those items are, so I can't answer your question.
. . But I think I have some valuable input.
A balance scale automatically demands thinking in the base-3 system.
You wish to measure whole-number amounts from 1 to 40 pounds
on a balance scale. .How many weights will you need?
The surprising answer is four weights: 1, 3, 9, and 27 (powers of 3).
To weigh 19 pounds of sand:
. . place the 1 and 27 in the right pan
. . place the 9 in the left pan
. . add sand to the left pan until the pans balance.
There is an elegant algorithm for determining where the weights should be placed
for any given amount. .If you (or anyone) is interested, I'd be happy to explain it.