Varnished items from older collections.

RDGAC · 26th March 2016, 01:43 PM

Norman,

Personally and professionally, I'd say that if you're careful then removing the varnish is generally preferable. Primarily this is for four reasons:

1) The lacquer's composition is unknown, and undesirable impurities may have been added to it during mixture (i.e. the purity of the original solvent is unknown, in addition to potentially damaging impurities entering the compound from the crushing and liquefying stages).

2) The lacquer's integrity is unknown; an uneven coat may have worn away in certain spots while remaining thick in others, or may never have been properly applied at all. Liquid coatings such as shellac (and also nitrocellulose lacquers such as Frigilene) are always problematic in this regard since they tend to run, and I tend to think that a coating that gives a false sense of security is as bad as no coating at all.

3) The lacquer is likely not to be up to scratch vis-a-vis long-term conservation properties. Shellac undergoes hydrolysis into acids (aliphatic and alicyclic acids, no less - from what little chem I understand, the more unstable sorts of organic compounds), which are in turn likely to cause damage to the object if they aren't neutralised. Frigilene and other nitrocellulose lacquers, in accelerated aging tests, have tended to peel off, discolour, and become difficult to remove. I myself have observed the characteristic yellowing of frigilene lacquer on a sword in the RDG collection, the lacquer having been in place approximately 20 years by that time. There's a rather good publication from the Getty Conservation Institute for anyone interested.

4) Frankly, that's a bloody ugly finish!

Let us know how you get on; there are a few objects in our collections that have been lacquered in their long (and long-suffering) lives, and I'd be interested to see the results of your work when planning any on these objects.

- Meredydd

Battara · 26th March 2016, 04:04 PM

Be very careful with the niello - a type of oxidation easy to take off and not to place back on. In fact, I'm not sure if anyone does niello anymore since the chemical fumes are very toxic.

Shakethetrees · 26th March 2016, 08:10 PM

Quote:

Originally Posted by Battara

Be very careful with the niello - a type of oxidation easy to take off and not to place back on. In fact, I'm not sure if anyone does niello anymore since the chemical fumes are very toxic.

Niello is a horrible mix of lead, and a little copper. When it's thoroughly mixed and still completely molten, a handful of powdered sulfur is mixed in, stirred, and poured into long thin (1/4") strips and allowed to cool.

Once a decorative design is chiseled into a piece of metal, the metal is heated and the niello strip is "mushed" into the design leaving excess. Or, it can be ground into a fine powder and applied like vitreous enamel and then fired. Allow to cool, and file the excess away, using a coarse single cut file. It's like filing graphite, soft, with a tendency to chip if you rush it. Polish any file marks polish with emery.

I did some of this while a student forty years ago, under a laboratory vent hood, and, believe me, it's a smoky, sulphurous, stinking mess. Glad I did it once or twice, but I don't think I ever want to do it again.

There are many formulae recorded, each with slightly different compositions and working attributes coming from early sources from around the world, but, I post this here for reference and not as a recipe, so unless you have laboratory ventilation, don't do it.

If repairs are absolutely necessary I would look into using an epoxy based mixture instead.

Norman McCormick · 29th March 2016, 11:47 PM

Hi,
Many thanks to all for your continued interest. I have taken on board your advice and suggestions and will proceed accordingly. The items in question are Zulu type spears, 1x Iklwa and another as yet undefined, which would appear to have been collected in the latter part of the 19thC or very early 20thC. I will post said items shortly.
Thanks once again to all who participated in the thread and gave of their experience and knowledge.
Regards,
Norman.

Tim Simmons · 30th March 2016, 01:42 PM

These three pieces were covered in thick yellowed old varnish. I took it off with Nitomors varnish remover from B&Q. Then ran the pieces through my hand smothered in olive oil, only the very best cold pressed virgin. If the wood has any patina It is brought back. If the item had no patina at the time of collection and varnishing it will be as it was, old with no patina.

Helleri · 1st April 2016, 03:45 AM

I wonder if you could get it to boil, flake, and become peel-able with something like hot air from a hair dryer.

30th March 2016, 01:42 PM	#5
Tim Simmons Member Join Date: Dec 2004 Location: What is still UK Posts: 5,843	These three pieces were covered in thick yellowed old varnish. I took it off with Nitomors varnish remover from B&Q. Then ran the pieces through my hand smothered in olive oil, only the very best cold pressed virgin. If the wood has any patina It is brought back. If the item had no patina at the time of collection and varnishing it will be as it was, old with no patina. Attached Images

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26th March 2016, 01:43 PM	#1
RDGAC Member Join Date: Mar 2010 Location: York, UK Posts: 167	Norman, Personally and professionally, I'd say that if you're careful then removing the varnish is generally preferable. Primarily this is for four reasons: 1) The lacquer's composition is unknown, and undesirable impurities may have been added to it during mixture (i.e. the purity of the original solvent is unknown, in addition to potentially damaging impurities entering the compound from the crushing and liquefying stages). 2) The lacquer's integrity is unknown; an uneven coat may have worn away in certain spots while remaining thick in others, or may never have been properly applied at all. Liquid coatings such as shellac (and also nitrocellulose lacquers such as Frigilene) are always problematic in this regard since they tend to run, and I tend to think that a coating that gives a false sense of security is as bad as no coating at all. 3) The lacquer is likely not to be up to scratch vis-a-vis long-term conservation properties. Shellac undergoes hydrolysis into acids (aliphatic and alicyclic acids, no less - from what little chem I understand, the more unstable sorts of organic compounds), which are in turn likely to cause damage to the object if they aren't neutralised. Frigilene and other nitrocellulose lacquers, in accelerated aging tests, have tended to peel off, discolour, and become difficult to remove. I myself have observed the characteristic yellowing of frigilene lacquer on a sword in the RDG collection, the lacquer having been in place approximately 20 years by that time. There's a rather good publication from the Getty Conservation Institute for anyone interested. 4) Frankly, that's a bloody ugly finish! Let us know how you get on; there are a few objects in our collections that have been lacquered in their long (and long-suffering) lives, and I'd be interested to see the results of your work when planning any on these objects. - Meredydd

26th March 2016, 04:04 PM	#2
Battara EAAF Staff Join Date: Dec 2004 Location: Louisville, KY Posts: 7,272	Be very careful with the niello - a type of oxidation easy to take off and not to place back on. In fact, I'm not sure if anyone does niello anymore since the chemical fumes are very toxic.

29th March 2016, 11:47 PM	#4
Norman McCormick Member Join Date: Oct 2007 Posts: 1,613	Hi, Many thanks to all for your continued interest. I have taken on board your advice and suggestions and will proceed accordingly. The items in question are Zulu type spears, 1x Iklwa and another as yet undefined, which would appear to have been collected in the latter part of the 19thC or very early 20thC. I will post said items shortly. Thanks once again to all who participated in the thread and gave of their experience and knowledge. Regards, Norman.

1st April 2016, 03:45 AM	#6
Helleri Member Join Date: Jan 2016 Location: Chino, CA. Posts: 219	I wonder if you could get it to boil, flake, and become peel-able with something like hot air from a hair dryer.