Brown wood was once the hight of fashion in peoples’ homes. Whether it be skirting boards, doors, doorframes, wood stain or varnish. Homeowners used to love that “natural wood feel” throughout the inside of their house.
Varnished woodwork still has its place, but the trend of dark timber throughout one’s home is slowly coming to an end. People like crisp, sharp lines now, and impeccable satinwood that looks clean and fresh. This presents us with a problem, because varnish seals wood completely and has a hard film that is designed to resist contaminants and not let other materials stick to it. This makes painting over varnished woodwork a challenge.
Unless you put a little bit of thought into your prep and paint system, then you will probably encounter problems such as tannins (stains) bleeding through your paint film, and lack of adhesion. You might find your paint chips over time, showing the varnish underneath.
Preparing Your Varnished Wood to be Painted
As already mentioned, the adhesion of paint to varnished wood can be problematic. So, there are a couple of things you need to do to combat this.
The first is to sand all your woodwork. I have read a few blogs online that tell you that sanding isn’t necessary, but as a Painter and Decorator, I can tell you that this is nonsense. You need to break the film on the varnished surface and allow the paint to bond to it. Plus, sanding creates a series of tiny scratches on the woodwork, which your paint fills and sticks to. This is called a “key”. So, skip the sanding and you risk your paint system failing.
Removing any dust is also important for adhesion. As you can probably guess, paint is a lot less likely to stick to a surface if it’s covered in a find dust. Besides which, dust in the paint is going to affect your finish anyway. Use a dust brush and tact cloths (links below).
The Best Primer for Painting Over Varnish
Even with proper prep, a normal undercoat will not stick to varnished wood. Instead, you need a specialist product designed specifically for the task in hand. Luckily nowadays we have an array of adhesion primers to choose from.
Not only does the adhesion primer need to stick to the varnished timber, but it also needs to block stains in the wood from seeping through the paint. For this reason, I often use an oil-based, or shellac-based primers. I have given you a couple of recommendations below.
This is a shellac-based paint designed to stick to difficult surfaces like varnished wood. It can be tricky to use, so use a foam roller to avoid roller marks, and cheap brushes because Zinsser BIN will wreck them!
Even though Zinsser BIN can be difficult to use, it has an added bonus: shellac also prevents sap bleeding through the knots in your wood. This isn’t normally a problem with fully varnished wood, but it can with woodstain. It’s just a case of ‘being better safe than sorry’.
Crown Trade PX3
This is an oil-based adhesion primer. Again, it is perfect for priming varnished wood before painting over with additional products. You’ll find it easier to use than Zinsser Bin, and better opacity. It won’t wreck your brushes either, although you will need to clean them with white spirits or turps if you want to save them.
The only downside of using Crown PX3 over Zinsser BIN for priming varnished wood is it won’t stop knot bleed. But as already mentioned, that isn’t normally an issue, and it will still stop all other stains from coming through the wood.
The Best Paint System for Painting Over Varnished Woodwork
Providing you carry out the proper prep and use a good adhesion primer, the rest of your paint system is down to personal choice. However, you do need to make sure that whatever paint system you use is durable. Otherwise, it will chip over time, especially on varnished wood.
Johnstone’s Aqua Guard
Regardless of whether I’m painting over varnished wood, previously painted wood, even new wood, I like using Johnstone’s Aqua Guard. You will need to apply a coat of Aqua Undercoat before applying the Aqua Guard.
However, it’s a water-based paint which is available in satin, matt, or gloss. It dries and cures as durable as any oil-based paint, which is perfect for using over the top of varnish. It comes in Brilliant White or just about any colour and will look mint for years.
Dulux Trade Satinwood
I thought I’d include a good oil-based system because I know some people still prefer to use this type of paint. There are a couple of advantages to using oil-based paint. Firstly, you know it’s going to be very durable. Secondly, it will block tannins and stains more effectively than water-based, which can only be a good thing when painting over varnish.
I chose Dulux Trade Satinwood because it’s one of the best on the market. It’s classed as “self-undercoating”, but I’d still recommend applying a coat of oil-based undercoat after your adhesion primer. This will help with opacity.
Dulux Trade Satinwood is easy to use, looks fantastic, is available in any Dulux Colour, and will last forever. It’s perfect for coating varnished wood.
Can you paint over varnished wood without sanding?
There are several products that claim to be capable of being applied over varnished wood without the need for sanding. However, I’d advise against it. You do not need to sand all the varnish off the timber, nor do you need to sand the varnish so it’s completely smooth. What you do need to do is create “a key”.
When you sand a surface, you’re essentially creating thousands of tiny scratches. This gives the paint something to grip onto.
How do you remove varnish from wood before painting?
You don’t necessarily need to remove varnish from wood before painting, but you can if you want to. Machine sanding is one way to do it. The other is to use a paint and varnish remove like Paint Panther.
As a Decorator, I used to burn paint and varnish to remove it with a heat gun. It was common practice at one stage, but it’s hard to find liability insurance to cover it nowadays, simply because it’s dangerous.
Can I use water-based primer over varnished wood?
There are several water-based primers that work nowadays. It isn’t just adhesion; you should also opt for one that blocks tannins and even knot bleed. I have two favourites: Zinsser BIN Aqua and Bedec All Prime. Either of these products will work well over varnished wood.
OK, you now know how to paint over varnished wood. Providing you follow the instruction on this blog, you shouldn’t have any issues. You can swap paint products if you need to. For example, if you use an oil-based topcoat, then you can get away with a water-based adhesion primer. That said, if you get the paint system wrong then everything may fail, so go with a system you have faith in.
How to Paint Over Varnished Wood – by Mike Gregory
What Other Decorators Have to Say
The prep as always is the key to success when painting over varnish. Pick your sanding medias, nothing too abrasive, you want to sand the varnish not the wood. Go with the grain with a light sanding pad and finish with mineral wool. I sometimes employ a green scourer like you might use for washing up. Wipe down lightly with a degrease or meths. Tack clothes are a good shout.
Next up is the primer. Caparol Haft Primer or your choice of grip primer.
Light sand (scourer) and tack cloth.
Apply the first coat of something suitable for this type of product. (Homework time)
Something that’s going to withstand the rigours of the particular furniture piece.
Light sand tack cloth and coat to finish.
A final coat in a clear lacquer isn’t a bad shout but not always necessary.
If you feel brave you can layer colours with chalk paint and sand through to bring under colours to the surface creating some spectacular finishes. This takes a bit more patience but can really pay off once you have a grip on the process.
I use Zinsser BIN, followed by Johnstone’s Aqua guard Undercoat, and Aqua Guard Satin to finish. Both water-based.
I used Zinsser BIN Aqua last month to prime varnished doors. Just sand the varnish to give a light key, then BIN, then undercoat, then two topcoats 😉
Degrease with methylated spirits, sand, dust off and then wipe down with tack rag. Then apply a coat of Benjamin Moore Stix bonding primer to the varnish, sand between coats with 180 grade sandpaper. Then apply your finish coats.