Wood Finish Identification & Finish Repair (oil, shellac, lacquer, and poly/varnish) | How To

There are different types of wood finishes and most of them don’t work together so if you need to touch up a finish, how do you identify what the finish is?

You can test the finish in a specific sequence. The first type of finish to test is oil. The main types of oil finishes are Boiled Linseed oil, Tung oil, and Danish oil. Any of these are compatible with each other and its easy to identify an oil finish. Put a drop of oil on the finish and let it sit for a few minutes. If it absorbs into the wood, it’s an oil finish. If it doesn’t, you have a shellac, lacquer, or poly/varnish type of finish.

Another hint to identify the finish is the furniture itself. Oil finishes are more common on fine furniture and mid-century modern furniture, so consider the piece you working on. If you see the grain of the wood in the surface of the finish instead of a solid film, it’s likely an oil finish.

If you’ve done the oil test on your piece, and it’s not an oil finish, the next thing to test for is a shellac finish. It’s important you test your finish in this order to determine what it is because some solvents work on multiple finishes.

To test for a shellac finish, you need to use a drop of denatured alcohol. Let it sit for a a few minutes, then try to dab it up with a rag or paper towel. If the surface is sticky and mushy, it’s a shellac finish. Shellac finishes are common on antiques, so that’s a hint when you look at the furniture.

The third test is to see if the finish is a lacquer. Lacquer is a common modern finish because it dries quickly, which means less chance for dust to settle on it and a higher rate of production in manufacturing. It’s not a common DIY finish because it is very toxic and usually applied with spray equipment.
To identify a lacquer finish, you need to place a drop of lacquer thinner on the piece. After about 20 seconds, dab it with a rag or paper towel to see if it’s sticky. If it is, you have a lacquer finish. If it isn’t, you have a polyurethane or varnish finish.

A polyurethane or varnish finish forms a protective plastic film. You need some very strong chemicals to soften the finish, which is why I suggest testing in the order of oil, then shellac, and then lacquer. By process of elimination, if nothing softens the finish, it’s polyurethane or varnish. Polyurethane and varnish will chip where the other finishes typically won’t.

How do you repair these finishes? Repairing an oil finish is simple. Just apply a new coat of oil.

Repairing a shellac finish is also easy, it’s just a matter of cleaning off the surface with warm water and a mild detergent such as dish soap, and then applying a new coat of shellac.

#woodfinish #polyurethane #shellac

[kbrollins]

I've understood the concept, but seeing how you actually spotted the material on the finish and WAITED 3 minutes was golden. Thanks!

[philgray]

Wish I had found this channel earlier. You have unlocked the mystery of our 135 year old table!

[pharoah]

‘I’ve spent hours and hours looking for how to test a finish. You can’t learn this process in jumbled bits and pieces because the testing needs to be done in a sequence. This video is so incredibly helpful. You are without a doubt my favorite woodworker on YouTube. Thank you so much for providing free information. You’ve made my life so much easier!

[kraptastic]

I needed a scientific method/ comprehensive education on this subject, from context of repair rather than refinish. This was a perfect delivery of the content with great jumping off points for the next content

[johnrogers-thorn]

Found this site this morning by accident repairing a 1870s chair. Boy wish I found it years ago. Fantastic videos buddy, I'll continue my viewing eagerly, thankyou.

[kestrelpounces]

I'm still new to this, but already whenever I'm searching for answer, I breathe a huge sigh of relief whenever I find one of your videos in the results! I know I can trust what you say not only to correctly address the problem, but also that your solution won't ruin the piece later on. Not to mention your relaxed low-key delivery in your excellent voice. Pretty sure I could listen to you read the phonebook, as they used to say. (Oh my, we're starting our second generation of people who don't know what a phonebook is, aren't we?! Doddering back to my workshop now....)

[ac]

I've watched this video repeatedly. So useful

[garmiellis]

Great sequence tip, I like it. Also, if you can't mamage to have solvents, but have a UV light in hand, flsh it over surfaces in the dark, and whatever glows orange is more likely shellac.

[marlenomahony]

Thank you so much . I have a bunch of old furniture from my great-grandmother and the finish needs some tlc but I had no clue what to use/do. So happy I found your channel.

[skyhawaii]

Another great video. You are a great teacher and provide vast knowledge that is second to none. I have 35+ years in painting and decorating, so I hope my word means a lot to anyone who watches your posts. Many thanks.

[donbushek]

Is there no need to distinguish between polyurethane and varnish finishes when it comes to over-coating the existing finish? Can I scuff sand a polyurethane finish and over-coat it with a varnish, and vice versa? And finally, what about Minwax Polycrylic?

[Mr.C-Mister]

Very easy on the ears and super informative. Thank you.

[ellenfoster]

Wow, this was fabulous! Wish I had seen this before I thought I’d quickly spiff up a shellac finish on an antique dresser. I assumed shellac given the age of the piece. However, at some time in the past, someone had applied poly. Much bigger job than I had planned on

[lovetrump]

Wonderful....now I gotta get to making a few repairs I have been putting off because I could not identify for sure what finish was used.
Thanks a MILLION!

[hijackn]

This is such a fantastic video. I’ve been following your channel for years now and this is one of the videos I keep coming back to.

[selenapollard]

It’s been a few years since this video was posted but thank you! Now I know how to start restoring all 6 of my sewing tables.

[dj]

I have a mid-century walnut table that I wanted to find out the finish as I wanted to re-new rather than start from new. This was super helpful. It was lacquer. A million thanks!

[IrishChippy]

Great video. Paint Thinners = Turpentine used for normal oil paints, varnishes and polyurethane. Lacquer and 'sand and seal' are nitro cellulose and need lacquer thinner for thinning. Denatured alcohol = Methylated spirits (UK and Ireland) is used in shellacs and can be used to make waxes instead of turpentine. Back in the 70's and 80's Methylated spirits had to be regulated because people used to drink it. Oils (Teak, Tung, Linseed and Danish) allow wood to breath somewhat. Mineral oil is the favorite for end grain chopping boards etc. It is food save and hydrates the wood. It is also used in creams, lotions and ointments etc. I now live in The Philippines where I will be soon teaching fine woodworking

[TippyPuddles]

This popped into my recommendations. I wasn't particularly looking for it but had in mind to fix the finish of the foot-board to my bed. It's an Ethan Allen French Country Slay-bed from the 80's. Wear is showing on the top of the foot-board from placing things over it and I use to sit in bed with damp long damp hair and the finish in that spot on the head-board is damaged too. I don't mind some nature wear on furniture, but now it's looking very tired. I have some woodworking knowledge to build, but little on repair. Thanks for the tip, I wasn't sure what finish it was and your other videos showed me how to approach the wear on the finish. Looks more like it's chipped away.

[kimberlythompson]

Thank you so much! 😃 This information is invaluable to a newbie furniture refinisher and explained in a way that's easy to understand.