I have found it aggravating to pick up a Lego model and pick up a gallon of dust with it. I like to try to keep my models refreshed, up to date, and dusted regularly.
Here is straight forward how to do it…
you will need:
an old toothbrush (unless you want to use a new one)
a small tupperware container full of slightly soapy water
(too much soap will actually be messy and may get hard to remove from the legos)
a towel for drying the lego elements
a drop-cloth or towel for the table
the model in question
To begin: you want to hit the major spots first. start, maybe, from one corner and then work your
way to the others.
1st, wet the toothbrush with the soapy water
start scrubbing in circles to pick up the dust and then brush everything in one direction to sweep it off the model or lego elements. This pattern helps to make sure that a necessary amount of dust and dirt is removed.
Not every dust particle will come off, but it will come off enough to leave your model nice and shiny.
When you have finished scrubbing the parts, use a nice clean rag to wipe away excess water,
note: some towels may leave their own dust behind, so make sure you use a clean rag.
Only do this in small bits. hit a small area and clean it, dry it, then wet swish the brush in the water a bit to refresh it, then hit another spot.
You may have to disassemble your model a bit to dust individual pieces so I recommend having the model's instruction manual nearby, if there is one.