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Some context for the question in the title: After years of fixing stuff around the house, I've developed a chronic form of sinusitis - the minimal amount of dust is enough to set me off. I do use a serious protection mask when working, but even the dust that remains in the air or the settles on the mask/face will affect me.

So I'm figuring out ways to do dust-free DIY.

Next up in the TODO list are a couple of wooden doors and window frames. I would like to give them a new layer of primer + lacquer on top of old (yellowish) but good state lacquer.

The product instructions insist on sanding after the primer and between layer of lacquer.

Why is that necessary? and what would be the consequences of not doing so? Are there any alternatives?

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    The sanding steps are to improve adhesion of the lacquer. – Nick2253 Jan 26 '15 at 16:29
  • if dust is the problem, could you try a full-face respirator with p100 filters, and wipe it down and store in a clean ziplock after using? – Anthony Bird Jan 28 '15 at 14:22
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As @Nick2253 commented, sanding between coats promotes better adhesion of the next coat. This occurs because a rougher surface has more area and "features" for the next coat to grab onto. That's why it's easier to scrape paint off of a smooth surface like glass than a relatively rough one like wood.

Sanding also helps remove any bumps from dust that's settled on the surface before the paint/lacquer/poly dries.

Since you're worried about dust, you could see if wet sanding is an option for the type of lacquer you're working with. Otherwise, know that "sand between coats" generally means a very light sanding which won't produce as much dust. You obviously don't want to sand heavily enough to remove all or most of the coat you just applied.

For poly, I sand with 220 or 320 grit with a hand sanding block between coats. The pressure I apply is basically the weight of the block, and I only make one or two passes. Most of the dust created is easily wiped up with a damp rag afterwards.

  • Thanks!. What would happen if I don't sand between layers? Would be a critical degradation from optimal bonding or would I hardly notice after some time? – maasg Jan 26 '15 at 20:21
  • It really depends on the type of coating and the manufacturer's instructions. I've used some that say, "Apply second coat within X hours of first without sanding. If time between coats is greater than X hours, lightly sand first coat." – Doresoom Jan 26 '15 at 21:13

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