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Sanding between varnish coats: how the next coat grips again
Short answer: only sand between varnish coats when the coat is dry enough, with a fine grit and only to make it matt and flat. The aim is adhesion and a calm surface, not taking the coat off again. After that all dust must go; dust under the next coat can be seen and felt. On edges and corners you work by hand; on flat parts a block can spread pressure evenly.
👷 Calling in a professional is never unnecessary. For a staircase, large furniture or a varnish coat that keeps reacting to the previous one, a painter or cabinet maker remains the safest choice. Have unknown old coats assessed before sanding them fine.
What matters most
- Keep the grit fine: a sanding block grit 220 is often the starting point for intercoat sanding. A sanding block grit 120 is too coarse for a good varnish coat and only belongs to repairing a bad spot.
- Flat with support: fold paper around a block or use a block on surfaces. With a putty knife with aluminium blade or a paint scraper first remove a run or dust point, instead of sanding around it.
- Clean before the brush: vacuum with a construction vacuum cleaner, wipe afterwards and protect the surroundings with masking film and blue painter's tape. Only then do a flat brush for lacquer, an acrylic brush or a foam roller come into play.
What do you need?
- A soft brush and a lightly damp cloth to remove dust from corners without making the coat wet.
- A test piece with the same varnish to feel drying time and sanding result.
- Good light at an angle over the surface to see shiny spots that are not yet matt enough.
How to do it
- Let the coat dry according to the directions and feel in a hidden place whether it no longer sticks.
- Remove runs and points carefully and then sand the whole surface lightly and evenly.
- Follow the grain and use almost no pressure on edges, where varnish is thinnest.
- Remove dust completely and check with a clean hand: the surface should feel smooth and dry.
- Apply the next thin coat and repeat only if the directions ask. Read preparation in our blog on putty knives, sanding tools and scrapers and technique in our blog on painting a door.
Working safely
Wear FFP2 dust mask and safety goggles for sanding dust and work gloves with nitrile coating against splinters and paint. Work with ventilation and keep dust away from a pilot flame or sparks. Do not dry-sand old unknown varnish without advice; a professional assesses that first.
Why does the first varnish coat feel rough?
Wood fibres can rise and dust can fall into the wet coat. Light intercoat sanding and good dust removal make the second coat smoother.
Can I wet-sand between all varnish coats?
Only if the varnish system allows it. Water can damage a coat that is not yet hard or give a haze. Follow the varnish directions and test on a test piece.
Intercoat sanding is making lightly matt, not starting again. Fine, dry and dust-free gives the best second coat.
Read also: How to paint a door: step-by-step DIY guide and How to paint a wall: DIY step-by-step guide
Where can you find everything for this job?
At Saniso, the online store for DIYers and professionals, you will find tools, materials and personal protective equipment for your job.
- Browse our construction tools and our workwear and safety.
- Create a customer account and order easily.
- Working on a bigger project or want to hand over the job? Request a project quote.
- Book a showroom visit, at least 24 hours in advance.
- Not sure which material suits your job? Get in touch with us.
In doubt about the approach? Feel free to call in a professional.
Saniso – Build your home with Saniso.
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