Talk:Varnish

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Varnish is also a class of hydrocarbons, I believe. In particular, if you leave a gasoline engine unused for a long time, it is said that the gasoline will settle out into gums, resins, and varnish. This meaning of the word is not explored in this article, but I don't have the knowledge to fill it in at this time --Mdwyer 22:20, 2005 September 6 (UTC)

I don't know about the gasoline. It seems entirely possible due to oxidation. Inside the cylinder or on other moving parts people talk about a "glaze" and "breaking the glaze" by a light abrasion or sanding when you're trying to avoid actual machining in an engine overhaul. The glaze is basically the burned hydrocarbons deposited on the metal where the friction or heat occurs.

Difference between Varnish and Shellac[edit]

shellac is NOT a varnish. varnishes, as the article points out, undergo chemical reactions after application. shellac does not. it is a so-called 'solvent release' finish. i.e., the solvent evaporates and leaves a film of the unchanged resin, which always remains soluble in the original solvent. in the case of shellac, this is methanol.methanol will remove a shellac finish.similarly, if a shellac finish is remove by scraping, the resulting powder can be dissolved in methanol and re-used. (i don't recommend it, but it is possible.)worn, crazed and otherwise damaged shellac finishes are also amenable to a treatment called re-amalgamation, where a coat of the solvent is applied (usually by sparaying) and simply allowed to dry. this cannot be done with varnishes. methanol and other alcohols have little or no effect on a varnished surface. i will wait to hear additional comments, but after a time I am going to delete shellac from this article, unless convinced otherwise.Toyokuni3 (talk) 17:07, 4 May 2008 (UTC)

I'm a contributor to this article but I haven't kept up with my WP ID. What you point out is absolutely true, and it is a weak point in the article. However, the original item that got the name of varnish oh-so-many centuries ago was re-soluble in its original solvent, just as shellac is. Dammar is one example of this and is widely available in art supply stores today.
One problem with understanding varnish is in semantics. Another is in chemistry. Frankly, varnish has not garnered much interest among the academicians who might clarify all the terminology. Conversely, varnish has been for centuries primarily an item of industry: people who are trying to make some (often not much) money but who are not concerned with regularizing terminology. Suffice it to say that today, in modern terms, "varnish" means any, and absolutely any, clear or semi-clear medium for providing a hard or semi-hard finish. —Preceding unsigned comment added by 76.198.65.250 (talk) 07:34, 4 June 2008 (UTC)
Leave shellac in place, because it's widely thought to be a "varnish". From an encyclopedia's point of view we should recognise this, and have content that clarifies the distinction. It's as useful and important for WP to say what it isn't, as to say what is.
That is an excellent point and one I've suspected since I started looking into these technologies. Working out the semantics between pages like varnish, shellac, enamel, and lacquer has been rough as authoritative sources such as dictionaries are nonspecific, and professional sources tend to conflict depending on geographic region and publication date. In these cases the best we can do is set up arbitrary or at least "best effort" scopes for article content. Concepts like "for the purpose of this article <topicname> refers to <chosen definition>". I've forgotten the state of this particular article, but from what I see, I agree, in modern terms, varnish refers to any clear or semi-clear medium for providing a hard or semi-hard finish. Shellac can fall into this category, but there is no need to describe shellac in detail, simply a quick WP:SUMMARY and reference to the main shellac article, and possibly explaination of how shellac does not fall into certain definitions of varnish. -Verdatum (talk) 15:59, 4 June 2008 (UTC)
It's your content too. Welcome to Wikipedia, if you don't like it, then you've as much opportunity to fix it as anyone. 8-) Andy Dingley (talk) 18:09, 4 August 2008 (UTC)

This article needs pictures[edit]

I think this article could use some pictures. I suggest:

  • A container of popular name-brand varnish. (Better yet, two or three, so as not to seem like we’re advertising.)
  • A woodworking project before and after application of varnish.

— NRen2k5(TALK), 02:06, 15 May 2009 (UTC)

I agree with your second suggestion, even though it will be difficult to impossible to convey the effect of well-done varnish in any kind of image, moving or still. Especially with figured wood, one needs to be right there to see it. Smaller pieces, such as string instruments, may be held at various distances in various lights, and turned this way and that for inspection... that's how the complete story starts to tell itself.
The first suggestion may not add much to the article, though. "Varnish" covers a lot of different substances and applications, and showing a picture of some labeled cans... that isn't what the article is really about. It's about the stuff itself, and some of the best will be found in unlabeled jam jars, with maybe a date and batch number scribbled on.
Now a cross-section micrograph of a cured varnish film and its substrate, that would add. IMHO. __Just plain Bill (talk) 16:04, 15 May 2009 (UTC)

Varnishing on boats[edit]

Always use spar varnish on boats as it has some flexibility.Multiple coats are needed-usually 6-8(or more) to give good protection.Varnish is not as water resistent as paint and much more difficult to apply ,though few would argue about its fantastic appearance if well done.Keep varnish for small pleasure boats like canoes, dinghies and small sailing boats or use in small areas on larger vessels as the upkep is far greater with varnish(dont use on work boats).Although modern spar varnishes are quite good they will still break down fairly quickly if left in the hot sun.Keep boats under cover when not in use to preserve the glossy finish.Never use anything else other than gloss on the exposed parts of a boat.Satin or other finishes are OK inside a bigger boat and are far easier to apply than gloss and look more like a classic oil finish.(Oil finishes have virtually no resistance to water penetration) Suggestions for good small boat varnishing are:Varish indoors only out of the wind and away from insects.The temp should be 15-22 celsius if possible.Use a very dust free environment-vacuum and use a tack rag after each sand down. Use cheap chip brushes that cost about $2.(wooden handle ,white hair, much less hair than an expensive brush which can cost up to $60 or more)Keep them clean with mineral turps and /or Sard Wonder soap ( which really is fantastic-made in Australia -see the web site)Much nicer to use than smelly turps.Make sure the LAST clean before use is turps, not soap.If you are loaded just throw the brush away each time .Sand wood until smooth with about 120grit paper then use varnish deluted about 10% with turps(especially on a hotter day)for 1st coat, brushing on thinnly. Sand with about 120-150 grit paper between the first 3-4 coats depending on how porous the wood is eg Meranti a common marine ply is quite porous(open grain).Each thin coat should be well brushed out -never mind the patchy appearance. Run hand over varish after each sanding to feel rough patches and resand . Then start applying thicker coats to get gloss after about 3-4 coats.Keep the light to one side ,lay on the varnish more thickly and dont brush out so much,work quickly , going back after a minute or 2 to check on runs.Use the tip of the brush to remove runs straight away.Keep checking with your eye down low to avoid "voids".Usually this coat is about 90% perfect.Sand lightly-240grit and try again until you get a even gloss with no voids or until your patience runs out.Boat decks are easy as they are flat but for items like centreboards or rudder do 1 side at a time for the final 2 or 3 coats.Clean brush real carefully and dont use for anything else.Just tip the end 4mm in the varnish before spreading to avoid drips.I find a 2"(40-50mm )brush works best but I keep a flat artist's brush (10mm x 2mm thick)for tight areas .Ive used this method on about 20 boats.Stick to paint if you are impatient!Harry the boatman.Sept 2011 — Preceding unsigned comment added by 219.88.97.148 (talk) 01:59, 12 September 2011 (UTC)

Difference between varnish and lacquer[edit]

The article currently reads, "Lacquer may be considered different from vanish because it can be re-dissolved later by a solvent (such as the one it was dissolved in when it was applied) and does not chemically change to a solid like other varnishes.[2]"

That is unclear. Traditional oil-painters' picture varnish is usually made from either dammar or mastic resin dissolved in turpentine. (Mineral spirits will not substitute, being too weak to dissolve the resin.) Picture varnish is not intended to be permanent, but rather to be removed and replaced when it becomes soiled or yellowed, perhaps every 50 to 100 years. It is removed using turpentine. I do not know if it changes chemically, but it certainly can be "re-dissolved later." Jive Dadson (talk) 06:39, 20 November 2011 (UTC)

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