Removing Varnish by Sanding You would use medium sandpaper (150 grit) to remove the top layers of varnish and then as you get closer to the original surface you want to remove the varnish from you would use finer sandpaper (220 grit).
Start with coarse-grit sandpaper (60-80 grit) to remove the bulk of the varnish. Progress to medium-grit (120 grit) and finish with fine-grit (220 grit) to smooth the wood surface. Preparation: Ensure the work area is well-ventilated. Wear a dust mask, goggles, and hearing protection if using power sanders.
Both varnish and rust are best removed with sandpaper or a wire brush. If you have areas with bare metal after sanding, you should definitely prime them. Use a rust protection primer for this. To help the paint adhere better, you can then apply a coat of To Bond & Block - MissPompadour Paint primer.
If you've got a piece with layers of old paint or thick varnish , then stripping is your best bet. Stripping is perfect for intricate details, carvings and stubborn finishes. + TIP: etch the surface of thick finishes like paint with a rough grit sandpaper to help the stripper penetrate.
60-80 Grit Medium grit sandpaper in the 60-80 range is versatile for smoothing bare wood before finishing. It's also excellent for gentle varnish removal, providing enough abrasion to strip down surfaces without gouging the wood.
Coarse-grit sandpaper (around 60-80 grit) is ideal for the initial sanding phase. It effectively removes the bulk of the polyurethane. Use a floor sander or a hand-held orbital sander for larger surfaces to ensure even coverage.
I typically sand in between coats with 320 or 400 grit. It's a very light sanding by hand just to remove any imperfections and rough up the surface. When varnish is dry and ready for another coat it will make a white powder when sanded.
An orbital sander will make this job much easier and quicker if you're removing varnish from a flat surface.
The allure of a fresh coat of paint is undeniable, but when it comes to varnished wood, skipping the sanding step can be a tempting shortcut with disastrous consequences. It's like trying to build a sandcastle on ice – the paint may cling precariously for a while, but eventually, it's all going to come crashing down.
If you are getting a rough finish after several coats of varnish, you may want to wet-sand the surface with 220 grit to level it out. Here I have leveled out the finish prior to the final coat and sanded it to 320 grit. I vacuumed the surface, wiped it down with a ragged wetted with mineral spirits.
Citristrip is a good alternative to Minwax If you're looking for a less toxic varnish stripper. Aside from Minwax, Citristrip was the best for removing finish. While the manufacturer recommends leaving it to soak in for at least 30 minutes, I noticed the finish bubbling up after only about 12 minutes.
Many wood surfaces are treated with finishes like varnish, lacquer, or sealants to enhance durability and appearance. Vinegar can strip away these finishes, leaving the wood vulnerable. This not only affects the wood's aesthetic but also its ability to resist moisture and other damaging elements.
Is it an acrylic resin varnish or a natural resin varnish? Damar resin, which you find in a natural resin varnish, will not dissolve in mineral spirits; for this, you need turpentine or a citrus solvent. An acrylic varnish, on the other hand, can be removed with either mineral spirits or turpentine or a citrus solvent.
Use a power tool like the random orbit sander on flat surfaces, and use handheld paper or a sanding block on irregular regions. Start with 150-grit paper and work your way up to 220-grit, removing any dust particles with a tack cloth or a lightly dampened rag as you go.
Selecting the Right Grit Sandpaper
For heavy sanding and stripping, you need coarse sandpaper measuring 40 to 60 grit; for smoothing surfaces and removing small imperfections, choose 80 to 120 grit sandpaper. For finishing surfaces smoothly, use extra fine sandpaper with 360 to 400 grit.
Using liquid sandpaper/deglosser or sandpaper helps dull any old paint, gloss, or varnish; preps the area for a new coat of paint or varnish; and helps bond the new finish to prevent it from chipping off easily.
Options for stripping furniture
You can use a citrus stripper (like Citristrip), a chemical one (like Formby's*), or you can just sand the old finish off (easier said than done). Spoiler alert: my favorite method, though, especially when the old finish is particularly dark or heavy, is to use all three.
This method requires caution.
A heat gun can soften the varnish, making it easier to scrape off. Hold the heat gun a few inches from the surface and move it back and forth. When the varnish starts to bubble, use a scraper to remove it.
Removing Paint or Varnish: For removing paint or varnish, use a coarse grit sandpaper, such as 40 or 60 grit, to quickly remove the old finish. Aluminum oxide sandpaper is a good choice for this task. Shaping and Rough Sanding: For shaping or rough sanding, use a coarse grit sandpaper, such as 40 or 60 grit.
Removing Varnish by Sanding
You would use medium sandpaper (150 grit) to remove the top layers of varnish and then as you get closer to the original surface you want to remove the varnish from you would use finer sandpaper (220 grit).
Re: removing varnish from furniture
There are two methods to remove the varnish on your table. Use an Orbital Sander in conjunction with 180 grit sandpaper. The other method is to use Bondall 1L Water-based Paint & Varnish Stripper.
Step 1: Sanding
Use 180-grit sandpaper and work the wood until the varnish is no longer glossy. For corners and other tight areas, use a sanding sponge or a bit of sandpaper. It is not necessary to remove all traces of the varnish, but it is critical to remove as much of the glossy finish as possible.
You will need a few sheets of 220-, 320-, 400- and 600-grit wet-or-dry sandpaper for sanding in the varnish. For dry-sanding between coats, use open-coat, self-lubricating 320-grit paper. A box of soft cotton rags from the paint store ensures that you won't run out of clean rags just when you need one.
– Existing Finish: If the wood has an existing finish that needs to be removed, stripping is typically the preferred method. – Surface Imperfections: If the wood has surface imperfections, scratches, or uneven areas, sanding is more appropriate.
This will ensure that the new varnish has something to bond to. The bottom line is that is it far better to remove any previous surface treatment - oil, sealer, polish, or varnish before re-applying varnish.