Why does nobody talk about how much filler shrinks after sanding?

I measured a repair yesterday and realized the filler went down almost 3mm after I sanded it flat, which surprised me since I always thought it stayed pretty close to where I laid it on.

2 comments

2 Comments

morgan_jenkins9012d ago

Oh man, have you noticed that too? I had the exact same thing happen on a bumper repair last week and I was shocked at how much material just disappeared after sanding. I swear I laid it on thick but after going through the grits it was way thinner than I expected. I think the filler contracts as the solvent flashes off and then the abrasives just eat it up faster than we realize. It definitely sneaks up on you if you aren't paying attention to the product's shrink rate or whatever.

patricia_wright12d ago

Wait, aren't you supposed to account for the shrink when you're mixing it? I always thought a little extra on the first coat would cover that but nope, it still vanishes like magic. Feels like there's some secret math the manufacturers aren't telling us about.