quinta-feira, 26 de março de 2009

Varnishes:Till Your Art and work may Call for its Assistance

Spirit and oil varnishes have a long history, the word varnish is often applied to the brushed on, thicker type of boiled finish, whilst it’s shellac base may well be called polish. Here we have two types of varnish, the spirit based and the oil based varnishes.

spirits of wine - rectified ethyl alcohol
ethanol, ethyl alcohol, fermentation alcohol, grain alcohol - the intoxicating agent in fermented and distilled liquors; used pure or denatured as a solvent or in medicines and colognes and cleaning solutions and rocket fuel; proposed as a renewable clean-burning additive to gasoline

shel·lac also shel·lack .n.
1. A purified lac in the form of thin yellow or orange flakes, often bleached white and widely used in varnishes, paints, inks, sealants, and formerly in phonograph records.
2. A thin varnish made by dissolving this substance in denatured alcohol, used to finish wood.
3. An old phonograph record containing this substance, typically played at 78 rpm.

seed lac - granular material obtained from stick lac by crushing and washing
lac - resinlike substance secreted by certain lac insects; used in e.g. varnishes and sealing wax
stick lac - lac in its natural state as scraped off twigs and dried.

Spirit Varnish.

This is a varnish that has the natural resins dissolved in alcohol, and shellac is the now most commonly used spirit varnish, although in the past there were many types of spirit varnishes in use. They can be be a very hard and resistant finish, and their clarity can enhance the wood with a fine finish, but do suffer from moisture penetration and marking, being also less resistant to common alcohol and spirit use.

Before modern finishes were developed, the spirit varnish and polish, was favoured for its clarity and high degree of fineness in the finish, although the harder varnishes had a tendency, with time, to become very brittle and develop fine crazing over the surface. There are hundreds of recipes for all types of varnish, here I will give some idea of how they were made, in the Dr,Ure’s Dictionary of 1840, he writes these recipes;

White Hard Spirit Varnish, or the white hard spirit of wine varnish,

Put 5 pounds of gum sandarac into a 4 gallon tin or bottle, with 2 gallons of spirits of wine, 60 over proof (too strong to drink) and agitate until all is dissolved, exactly as is directed for the best mastic varnish, recollecting, if washed glass is used, that it is convenient to dip the bottle containing the gum and spirits into a copper-full of hot water every 10 minutes- the bottle to be immersed for only two minutes at one time- which will greatly assist in the dissolving of the gum; but, above all, be careful to keep a firm hold of the cork of the bottle, otherwise the refraction will drive the cork out with the force of a shot, and perhaps set fire to the place ! The bottle, every time it is heated, ought to be carried away from the fire (remember this is alcohol inside) and the cork should be eased a little, to allow the now rarefied air to escape: then driven tight, and the agitation to be continued in this manner until all the gum is properly dissolved; which is easily known by having an empty tin can in which to pour the vanish, until near the last, which is to be poured into a gallon measure. If the gum is not all dissolved, return the whole of the mixture into the 4 gallon tin/bottle, and continue the agitation until it is ready to be strained, when every thing ought to be quite ready,and perfectly clean and dry,as oily tins, funnels, strainers,or any thing damp, or even cold weather, will chill and spoil the varnish. After it is strained off, put into the varnish 1 quart of very fine turpentine varnish, and shake and mix the two well together. Spirit varnishes should be kept well corked: they are fit to use the day after they are made.

Brown Hard Spirit Varnish.

Brown hard spirit varnish is made by- putting into a bottle 3 pounds of gum sandarac, with 2 pounds of shellac ( shell-lac) and two gallons of spirits of wine, also 60 over proof; proceeding exactly as before directed for the white hard varnish, and agitating it when cold, which requires about 4 hours of time, without any danger of fire; whereas, making any spirit varnish over heat is attended with a degree of danger. No spirit varnish ought to be made near fire or candle light. When this brown hard is strained, add 1 quart of turpentine varnish, and shake and mix well: next day it is fit for use.

French White Spirit varnish.

The following are reckoned to be good French recipes for varnishes:

White spirit varnish – Sandarac, 250 parts, mastic in tears, 64; elemi resin, 32; turpentine (vernice), 64; alcohol, of 85 per cent,1000 parts by measure. The turpentine is to be added after the resins are dissolved. This is a brilliant varnish, but not so hard as to bear polishing.

For large quantities of the spirit varnish, Dr Ure recommends the following:

“ When large quantaties of spirit varnish are to be made, a common still, mounted with its capital and worm, is the best vessel employed for containing the materials, and it is placed in a steam or water bath. The capital should be provided with a stuffing-box, through which a stirring-rod may pass down to the bottom of the still, with a cross piece at the end, and a handle or winch at the top. After heating the bath till the alcohol boils and begins to distil, the heat ought to be lowered, and the solution may continue to proceed in an equable manner, with as little evaporation of the spirits as possible. The operation may be supposed to be complete when the rod is easily turned round. The varnish must then be passed through a silk sieve of proper fineness; then filtered through porous paper, or allowed to clear leisurely in stone jars. The alcohol which has come over should be added to the varnish, if the just proportions of the resins have been introduced at first”.

If I can get hold of the software for text recognition, I have a large number of recipes, in many books, and covering many periods of history, and it would be good to post them on the net. However the work load to simple read and then rewrite these is rather greater than I would like to undertake at the moment, text recognition would allow me to scan and copy into word, direct, and then also give me the opportunity to translate into other languages and also copy and translate Italian and Spanish reference into English.

A Treatise of Japaning and Varnishing; Stalker and Parker, 1688.

This excerpt gives recipes that have not changed over the three centuries that have now passed since the writing of their treatise.

“Take one gallon of good spirit, and put it into as wide a mouthed bottle as you can procure, for when you should afterwards strain your varnish, the Gums in a narrow mouthed bottle mat stick together, and clog the mouth, so it will not be easie task to sparate or them them out. To your spirits add one pound and a half of the best seed-lac, let it stand the space of 24 hours, or longer, for the gum will be better dissolved, observe to shake it very well, and often, to keep the Gums from clogging or caking together. When it hath stood for some time, take another bottle of the same bigness, or as many quart-ones that will take your varnish; and your strainer and flannel made as foresaid in the book. Fasten it to a tenter hook ( it was the custom for butchers to hang meat and game on a hook, until the meat relaxed and became more tender, thus getting the name of tender or tenter hook) against a wall, or some other place that is convenient for straining it, in such a posture, that the end of your strainer may almost touch the bottom of your tin-tunnel, which is supposed to be fixed in the mouth of your empty bottle, on purpose to receive your strained varnish. Then shake your varnish well together, and pour or decant into your strainer as much as it will conveniently hold, only be sure to leave room for your hand, with which you must use to squeeze out the varnish, and when the bag by so doing is almost dry, repeat it, till all your strainer is being almost full of dregs of the Gums, shall (the moisture being all pressed out) be required to be discharged of them; which faeces or dregs are of no use, unless to be burnt, or fire your chimney. This operation must be continued, till all your varnish is after this manner strained; which done, commit it to your bottles close stopt, and let it remain undisturbed for two or three days, then into another clean empty bottle pour off very gently the top of your varnish, so long as you oberve it to come clear, and no longer, for as soon as you observe it to come thick, and muddy, you must by all means desist: and again, give it time to rest and settle, which twill do I a day or two; after which time you must attempt to draw off as much of you fine varnish, and having so done you may lay it up, till your art and work may call for its assistance. Tis certain, that on any emergency or urgent occasion you may make varnish in less time than 24 hours, and use it immediately, but the other I recommend as the best and more commendable way: besides, the varnish which you have from the top of the bottles first poured off, is of extraordinary use to adorn your work and render it glossy and beautiful. Some artists, through haste or inadvertency, scruple not to strain their varnish by fire or candle-light; but certainly day-light is much more proper, and less dangerous; , for should your varnish through negligence or chance take fire, value not that loss, but rather thank your stars that your self and work-house have escaped. Should I affirm, that the boiling the Lacker and Varnish by the fire, were very prejudicial to the things themselves, I could easily make good the assertion; for the y are as well and better made without that dangerous element, which any after this caution will undertake, they may feeling assure themselves that tis able to spoil the experiment and operator. On the other hand, no advantage or excellence can accrue either to Lacker or Varnish, especially when, as some of them do, tis boiled to such great a height, that this Aetna is forced to throw out its fiery eruptions, which for certain consume the admiring Emperdocles, who expires a foolish and negligent Martyr; and it would almost excite one’s pitty, to see a forward and ingenious undertaker, perish in the beginning of his enterprise; who might have justly promised to erect a noble and unimitable work of art, as a lasting monument of his fame and memory: but (unhappy man) his beginning and his end are of the same date; his hopes vanish, or frightfully represented in a Puppet-shew, or on a sign-post.

To make shell-Lac varnish.

Whosoever designs a neat, glossy piece of work, must banish this as unserviceable for, and inconsistent with, the rarities of our art. But because tis commonly used by those that employ themselves in varnishing ordinary woods, as olive, Walnut, and the like, tis requisite that we give you directions for the composition of it, and if you conveniency or fancy lead that way, you may be supplied with materials for the performance. Having therefore in readiness one gallon of the best spirit, add to it one pound and a half of its best Shell-lacc. This mixture being well stirred and shaked together, should stand about 24 hours before tis strained: You might have observed, that the former varnish had much sediment and dregs; this on the contrary has none, for it wholly dissolves, and is in consequence free from all dross or faeces, tis requisite however to strain it, that the sticks and straws, which are often in the Gum, may by this percolation be sparated from the varnish. But although this admits of no sediment, and in this case differs from the aforementioned varnish, yet tis much inferior also to it in another respect; That this will never be fine, clear and transparent, and therefore twill be lost labour to endeavour, either by art or industry, to make it so. This shall advantage however doth arise, that you need not expect or tarry its perfection, for the same minute that made it, made it for use. This, has I hinted before, is a fit varnish for ordinary work that requires not a polish, and look well for the present, yet like the handsome lady’s beautiful face, it hath no security against the injuries of time; for but for a few days will reduce it to its native mist and dullness. Your common varnish-dawbers frequently use it , for tis doubly advantage to them, having greater body than the Seed-lacc, less labour and varnish goes to the perfecting of the work, which they carelessly slubber over, and if it looks tolerably bright till tis sold, they matter not how dull it looks afterwards; and lucre only being designed, it can compass that, farewell and admiration. Poor insufficient pretenders, not able to make their work more apparent, or more lasting than their knavery ! And tis pretty to think that this same misty cloak will not cover the fraud or the impostor! That the first should be a foil to the second, and the dull foggy work serve only to set off the knavish artist in the most lively colours ! But to conclude, if with a pint of this varnish you mix two ounces or more of Venice-turpentine, it will harden well, and be a varnish good enough for the inside of drawers ( remember that it is not necessary to use good hard varnish in every part of a piece of furniture, a lesser quality can surfice for areas of less wear), frames of tables, frames of chairs, stools, or the like. Painters lacker (lacquer) made also from this varnish, and something of a larger quantity of turpentine put to it, serves very well for the lackering of coaches, house, signs, or the like, and will gloss with very little heat, and, if occasion be, without”

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