"Molly Brown" wrote

I need a product that has the same thickness and consistency and
waterproof quality as lap cement but is clear or transparent and not
black or runny like Thompson’s. If anyone has any ideas I would
greatly appreciate it.

Molly, are you trying to redo a roof? We can help better if we know the
project as there are too many variables in what would be suggested. For
example, if it needs to withstand a bit of cleaning (or a lot) then it's a
different material from one used where it will be undisturbed.