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35 year old rimu coffee table

I bought an old rimu coffee table that's been sitting in a garage for the last few years. I really like how it looks so my plan is to clean it thoroughly and then apply pure tung oil for protection. It doesn't look varnished or lacquered. It feels like very smooth natural wood with a light sheen on the edges so maybe oil? It's in good enough condition that I don't want to take a sander to it.

The question: is it ok to use pure tung oil if I don't know what the original finish was?

Graphus
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user13716
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  • Hi, welcome to StackExchange. We have numerous previous Answers here that touch on how to clean furniture (not to mention the wealth of information there must be online on this topic). So my only question would be why do you want to use pure tung oil? Is there something special/unique you believe it provides? Or is it just that you have some and are looking for a project to try it on? – Graphus Sep 08 '23 at 15:20
  • @Graphus maybe I'm just buying into the hype but tung oil is a similar price to more modern oil based finishes like kitchen counter oil and I wanted to try it. I heard linseed oil which is easier to get will yellow the wood which I wanted to avoid. Regarding cleaning, there is a lot of contradictory noise in the search engine results from general content creators and I couldn't find anything specific to a probably finished but long neglected bit of furniture. – user13716 Sep 08 '23 at 21:34
  • It isn't a question of "cleaning" . There is very likely an existing, commercially applied film finish of some type that will have to be stripped/sanded off as well as what appears to be some damage to the surfaces that will also require proper repair and sanding. Tung oil is OK afterwards, but a table (especially the top) kind of wants some sort of protective finish on it. Oil offers very little protection on it's own. – gnicko Sep 08 '23 at 23:37
  • Tung oil is greatly over-hyped unfortunately. All oils add some yellow component to wood (or appear to, wetting just with water can bring out yellowness despite water being colourless). And over time all natural oils, including tung, darken towards an amber/tan colour. So think of that as issue #1. A secondary issue with tung oil in particular: it's very slow to build up to look good, because of the number of coats needed, and the slow/very slow drying time. But the main thing is that unmodified oils are actually terrible finishes for furniture, including tung oil despite [contd] – Graphus Sep 09 '23 at 05:15
  • ...its much-touted better water resistance compared to linseed oil. Now those issues aside, oils have to go onto bare wood (or onto previous coats of oil) and that's not what you have here. Commercial factory-produced furniture will either be lacquered or have a conversion varnish on it, 99.99% of the time. This coating can be very thin (which is the main reason these good finished don't hold up well on mass-market stuff) but unless actually scrubbed off the surface by sustained extra-enthusiastic cleaning some finish must be assumed to be present in the wood fibres or on the surface. – Graphus Sep 09 '23 at 05:20

1 Answers1

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is it ok to use pure tung oil if I don't know what the original finish was?

The short answer is no.

There are some finishes that it would be OK to apply tung oil to1, but with commercial factory furniture it's extremely unlikely any such finish was used.

So instead you're faced with some amount of remaining commercial finish, either lacquer2 or conversion varnish. No oil should be applied to either of these, even if you wanted to use an oil for a table (which is questionable, because tables really require more protection than straight oils can provide, even tung oil).

What instead
There's likely to be some amount of the original finish still present in or on the wood (except in areas where it has been worn down to bare wood and there appears to be a lot of edge wear here from heavy use or excessive cleaning).

So if you don't want to strip back to begin again with bare wood the viable options are wax, or a harder finish.

Wax can be used because waxes can go on top of anything.

Finishes that dry hard can be applied to other hard finishes, as well as bare wood, and even if they don't bond to the previous finish chemically they can grip to the surface well enough for practical purposes. They then cure hard enough that the surface isn't permanently gummy or sticky.

See previous Answer for more details on surface prep.

1Basically, any straight oil or simple oil finish.

2Now multiple kinds, although formerly it was 100% nitrocellulose.

Graphus
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