Cleaning antique mahogany dresser

[Gold Coaster]

Hello everyone, I’m brand new to this forum and would like to ask a question about a 150 year old Mahogany dresser that my father French Polished back to its original glory more than 50 years ago. He is 90 years old now and his memory is fading. There is an oval mark on the top corner of the dresser where someone recently sat a bottle of spray bathroom cleaner. I’m trying to find ways to remove the mark and polish the top back to its original shiny finish. In his shed I found a bottle of Methylated Spirits, very dark brown in colour. When shaken, the mixture turns a honey colour. He tells me that is his Shellac-Metho mixture (and there is another bottle somewhere in the shed containing his mix of Linseed Oil that I am yet to find). He said to make a small linen pad with thick cotton inside, dip into the Shellac mixture, wring out, then wipe back and forth across the mark until it the surface begins to go sticky. Then stop, and repeat the next day. And the next, and the next.

I am up to day 3 now and don’t see anything happening. Do you think I am doing something wrong?410662410661410660

[q9]

Bleach is pretty basic, so will tend to eat plastics and paint. And shellac. Being recent damage maybe it is still sitting in below the surface of the wood? You won't get far if that is the case. If you get bleach on you you'll notice it feels greasy - one of the signs a liquid is a base - and I'd guess it isn't letting anything bond to the wood. Need to counter its affects first I would think. Obviously acids neutralise bases, but I'd be cautious of throwing any old acid on there...

wood chemistry is not my strong point in these kinds of situations...how colour/structure may be affected etc...

[ian]

This is my guess

1. your father's shellac mix is old and no longer effective. Mixed shellac has a shelf life of about 3 years. It's quite possible your dad's "mix" is more than 10 years old. I know my father used to only toss his old shellac mixes when he made a new one and it could be years between needing to make up a mix.

2. it's also possible that there's too much water in the mix. Metho absorbs moisture from the air.

3. it's possible that the dresser has multiple coats of wax, which would need to be removed to get to the point where the original shellac polish can be reactivated.

[Gold Coaster]

Thankyou!

[Gold Coaster]

Im sure it would be about 10 years old. Thankyou, I would not have thought of that. I will mix up a new bottle today and see how it goes. His instructions to me were : pour shellac flakes into bottle, cover them with mentholated spirits, about 1 inch higher than the flakes. Leave for 24 hours. Correct?



This is my guess

1. your father's shellac mix is old and no longer effective. Mixed shellac has a shelf life of about 3 years. It's quite possible your dad's "mix" is more than 10 years old. I know my father used to only toss his old shellac mixes when he made a new one and it could be years between needing to make up a mix.

2. it's also possible that there's too much water in the mix. Metho absorbs moisture from the air.

3. it's possible that the dresser has multiple coats of wax, which would need to be removed to get to the point where the original shellac polish can be reactivated.

[ian]

Im sure it would be about 10 years old. Thankyou, I would not have thought of that. I will mix up a new bottle today and see how it goes. His instructions to me were : pour shellac flakes into bottle, cover them with mentholated spirits, about 1 inch higher than the flakes. Leave for 24 hours. Correct?there is also an issue of how old the shellac flakes are. This I'm less certain of as I used to keep mine in dad's freezer.

when buying mentholated spirits, not all methos are equivalent. Some of the cheaper brands contain more than 20% water. You want to use as pure a metho as you can find. Sorry, but from Canada I can't really advise a reliable brand.

[Xanthorrhoeas]

All of the above suggestions are certainly very possible causes or contributors of the problem you are having.

As to metho (really denatured alcohol - they no longer add methyl alcohol to it to make it poisonous for consumption) - In another posting over the last couple of days Woodpixel has commented that a pure so called metho "methylated" spirits (not mentholated btw) is available as something called IMS from the Paint Place. I have no experience of that myself and find Diggers metho works fine for me (but maybe I've been lucky).

Age of shellac: I have also read many times that shellac gets old and fails to work properly. I have no experience of that either but maybe I've always used mine up before ... (but maybe I've been lucky)

However, I think that you have a worse problem to consider. It looks to me as if the bathroom cleaner has bleached your timber. Even if you can get a great coat of shellac over it (and there are some issues with what your Dad has recommended there) if the timber is lighter than the other mahogany then the mark will remain visible anyway. That would be compounded if the bleach is still active in the timber but I hope that you have neutralised that.

So, if the timber is bleached, what do you do? French Polished antique furniture has the greatest value when it has its original finish. Yours has already been repolished so that gives you more freedom. But, be aware that you are always going to have a sign/mark of this damage unless you strip the entire top, sand it back to bare timber and then repolish the whole top.

I know the mark is unsightly, but antiques inevitably gain signs of wear and tear and damage over the years - it is called patina - and if the piece has an original finish it is better to accept the damage - maybe disguise it with a dark wax - than to blow away the value by refinishing. Patina is an important facet of antiques and adds value, not detracts. I do understand that a very new bleach mark does not feel like that but, over time and coupled with other marks it may not be so important.

If (and only if) the timber is bleached (but the bleach has been washed off/neutralised) and you really want to try to make the top as perfect as you can then you will need to gently sand a patch around and including the mark. Start with a fairly fine paper and take your time (say 240 grit) and use some metho to soften the shellac. There are commercial restoration products that essentially do this (I think UBeaut sell one). If you are just using metho and fine paper then stop when the mark has disappeared, i.e. you are down to bare timber in your patch. Then sand - without metho with wet and dry paper all the way in small jumps (320, 400, 600, 800) up to 1000 or 1200 grit. At that stage you remove the dust and make up your pad (rubber) and your metho & shellac mix (or perhaps buy a ready made mix). Then you dilute the mix down to 25% shellac 75% metho - very dilute so that each coat is very thin and will also dry fast. You can probably get about 5 coats on per day before drying overnight. Then, next morning, rub the surface back with 1000 grit paper to smooth it down before applying another 5 very dilute coats. Repeat until you are happy with it.

Patching a mark/patch in a finely polished surface is very difficult even when you are an experienced polisher - there will always be a sign left. Repolishing an entire top always gives a better result in my experience, but is a big challenge for a novice.

Good luck.

David

[Xanthorrhoeas]

BTW, vinegar will neutralise bleach and then can be washed off with water. The shellac adjacent won't be damaged as long as you dry it off thoroughy straight away. Old shellac is pretty tough stuff. But, you will need to let the wood dry out well afterwards.

[Xanthorrhoeas]

Sorry! Where are my manners? Welcome to the forums. Post as often as you want, give us photos where possible and enjoy!

David