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I am pretty confused over all of this. I have done a search, and didnt get the info I was wanting.
What I want to know is………exactly what is “urethane”( or “polyurethane”)…..is it a natural product. ie: plant based somehow or is it synthetic?
I know that when applying these finishes that it is the solvents that make all the smell and cause headaches.
Can I mix up my own ‘stuff’ that will perform in a similar way without all the toxic fumes?
I am wanting a ‘safe’ finish mostly for my own well being and also so I can market it as safe. I am considering shellac, but can I mix that with oil and wax to make my own brew?
Lots of questions I know, but I am very unsure as to what is in the tins of finish I see in the shops. I DO know there are no Danes in Danish oil, and that there is no ‘teak’ in scandanavian teak oil either.
thanks for any help.
Replies
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AJ,
I'm no chemist but....Yes "urethane" is a synthetic. The "poly" I believe is short for a type of polymer used in the urethane. I sure you have heard of poloypropolene rope. You know, that hard plastic stuff?
The industry is pretty competitive, so where to get the formula could prove to be quite a challenge.
FWIW, I resisted the use of polyurathne for years, I only started using regularly within the last decade or so. I would highly recommend MinWax Wipe On Polyuerethane, it comes in a satin and semi-gloss. I'am extremely happy with it.
As for safe finishes, most oil based finishes are primarily natural. Spar varnish and shellac to name just a couple. It's the solvents used in thinning, as retarders, hardners, that present the most problems, I think. Spraying oil based lacquer is the most toxic.
Shellac is the most "natural" it is actually made from the secretions of the Lac Beetle found in India and wax. Yes, you can make your own shellac and can buy the ingredients through Garrett Wade, Constintines, and other mail order houses.
In the February 2000 issue (No.140) of
i Fine WoodWorking
there is a good article on making your own waxes if that interests you as well.
Water borne finishes are the safest. I'm sure that they day is not that far away that most of the oil based finishes will be banned. Personally, I tried a water based finish once, that was back in the 80s sometime, damn near ruined the piece and I haven't used one since, nor do I ever intend too.
Ultimately, though, the choice of finish depends upon how the piece is used. Whether it will see hard use such as a kitchen table to a piece such as a pie crust table placed in the corner of a room with a portrait on it.
If I would be forced to choose only one finish for interior pieces, it would be shellac. Not only will it give you a durable finish, but is also excellent as a sealer.
As to the so called "Danish" oils, and what not, they are really nothing more than wood conditioners, IMHO. Tung oil is a good finish but has moderate to light protection, and is used a lot with other types of finishes. Spar varnish as an example will also contain tung oil. One decision that needs to be made; do you want a film finish or a penetrating finish?
i Great Wood Finishes
by Jeff Jewitt and
i Understanding Wood Finishing
by Bob Flexner would also be worth checking out.
Dano
*DanoSomehow I just knew you would be the 1st to reply............good onya mate!now.........what I prefer is penetrating finishes cos to me they enhance the colours and grain and dont create a noticable film. I went to this site........http://www.naturalhouse.co.nz/home.htmlfor a selection of 'natural' finishes. The advantage with this place is it is only 45 mins drive away. quite useful.One drawback is the price......2 - 3 times that of Danish oil. What I dont want is to be breathing in solvent fumes from a finish and dont want to create a film. Can shellac be mixed with oil and or wax? or do put on oil for colour/ grain enhancement, then shellac. or will this not work?Also...........what is "varnish". is this one plant based? and are the solvents in this just as noxious as the urethanes?thanks for the book referrences and the help.AJ
*AJ,I lurk about in this room quite bit, other than the hand work I do this is my favorite wood working operation. You'll also catch me alot over in Tools, and Joinery. Any who...Thanks for the link, I'll bump around in there when I have more time.So, your prefer penetrating finishes? Well, first off, I really haven't noticed where a penetrating finish is better than a film finish in bringing out the grain in general, there is one exception that I will get to later. A film finish does penetrate, providing the wood is not sealed. I posted a pic over in the Gallery of a Western Red Cedar door I did awhile back using Interlux Schooner varnish which is their "traditional" spar varnish. It's not a real good pic, let me know if you don't like how the grain turned out on the kick panel;)For a penetrating oil only, my favorite is simple boiled linseed, buffed out using beeswax. Problem is that most folks don't care for the maintenance. Rule of thumb here in finishing is, once a day for a week, once a week for a month, once a month for a year, and once a year forever. Something I learned way back in junior high about linseed oil and Cherry is that it will really "pop" the grain. Let it dry for a week or two and apply any type of oil finish to it or just bees wax, it really looks fantastic. Why this seem to hold true for Cherry, I don't know.Getting back to shellac, maybe I wasn't very clear, since shellac is essentially beetle spit, wax, ethonal, Isopropanol, water, and Methonal. Don't ask about the guy that did all the reasearh to figure out that a Lac beetle's spit made a good finish, I don't know the answer to that one either. I have never heard of mixing oil into it. You thin or "cut" it using denatured alcohol. You can dewax shellac by decanting it. This will basically give you a clearer finish. The stuff you get out of the can is either white or orange shellac. The white actually will dry clear, the orange dries with a slight amber tint to it. Behlen manufacters dried shellac flakes in various tints, all you do is add a good quality denatured alcohol. Shellac can by put over any type of stain. Zinsser claims that any universal tint can be mixed in. So, as far shellac in cans go they are the brand I use and up here just about every body and their brother sells it, they market it as "Bulls Eye".Spar varnish is based from a vegetable plant of some sort, as to the exact composition I can't tell you for certain. I do believe that they are less "noxious" than the polys.FWIW, even the water based stuff that I've seen says "Harmful if Swallowed" on their cans.;) But if you are looking for a finish that you can drink, go down to your local apothecary and get a bottle if mineral oil, that's what you would use as finish for a butcher block counter top.Hope this helps.Dano
*Let me add a couple of things to Dano's post. First, since the mid 1970's all indoor finishes are required to be non-toxic when fully cured. It makes no difference whether the finish is oil, water or alcohol based. All are toxic when wet; none are toxic when cured. You can't drink shellac or waterborne finishes.All varnishes contain "plastic" of some type. The resins are genenally alykd, phenolic or some other "plastic". Spar varnish is made with a varnish that starts off as tung oil (for the good marine ones) with phenolic resin and UV inhibitors as well as mineral spirit thinner. Other clearer varnishes are linseed oil or vegetable oil base now days with alkyd resins. "Polyurehane Varnish" is standard varnish with the addition of polyurethane which makes the product more scratch and heat resistant.Finally, I would recommend the purchase of "Understanding Wood Finishing" by Bob Flexner and/or "Great Wood Finishes" by Jeff Jewitt. Both have excellent discussions of the various finishes, how to chose the proper one for the application and then how to apply it. For anyone getting started in finishing they will get you up to speed quickly.
*AJ,The following is finishing info as it applies to floors, ie, high-wear areas, but should be generally applicable.b PolyurethanesSolvent-based --- very toxic fumes, hard shell finish, yellows with exposure to UV.Oil-based --- not as toxic, not as hard, yellows worse.Water-based --- non-toxic, non-yellowing, not as hard. The water-based has two disadvantages -- the first coat raises the grain and because it takes 7 - 10 days before it is hard enough to cut back (friction melts it earlier) it is very difficult to correct.It has a slight bleaching effect on the timber and does nothing to bring out colour or figure.b Penetrative finishes.I used a finish I mixed myself -- 1/3rd pure turpentine, 1/3rd boiled linseed and 1/3rd pure tung oil. As all oil tends to bleed back slightly, I buffed out with paste-wax.In practice, in wet areas my spec was 1 coat solvent-based poly as a grain sealer + 3 coats water-based.For oiled floors -- oil applied to saturation, excess mopped off and paste-wax applied and buffed in.IMO there isn't a finish that can touch oil for bringing out the beauty of the timber, (I did a Rimu floor with it once that looked magnificent) -- it needs a lot more work but it has got the great advantage that you don't have to worry about dust or hairs in the coat
*Here is a link that might help you sort out some of the finishes and their characteristics. I do not agree with Howard's assertion that "all" varnishes have "plastic" added to them. Varnish has been around for 100's of years--before plastics were produced. I personally do not like poly finishes because I feel they lack depth. There are varnishes available that are not polyurethane. I do agree about looking at Bob Flexner's book Understanding Wood Finishes. Good luck.http://members.home.net/jdkx2/links.htm
*AJ is in New Zealand. All finishes in the U.S. are non-toxic when dried due to legislation. New Zealand might not have the same laws (or, might have even stricter ones).Like Howie, I don't know of any varnish that doesn't contain a plastic. Old (ollllld) varnishes used resins like Copal and Sanderac. I don't believe they are available any more.Dave
*Gretchen, a small point but all "modern" varnishes contain resins that are plastics. The first was phenolic resin developed in the early 1900's and still used in spar varnishes, followed by alkyd and then polyurethane. I doubt that you can get a natural resin varnish any more.
*Thanks for all the help, at least now i know what things actually are. I will endeavor to get my hands on a copy of those books.Gretchen........thanks for the link.Ian , Rimu is a beautiful timber isnt it? I did a floor once in recycled Matai, the colours ranged from light honey to almost black. It looked amazing. Thanks for the 'recipe'.What I am now thinking of doing is ( this is for furniture ) a mix of turps,linseed, carnauba (sp?) and beeswax. the turps is a thinnning agent only I know and will evaporate out. I am making the assumption that the harder wax will retain the oils and help prevent drying.Will use shellac for some applications.My reasons for avoiding 'urethanes' is that I dont like the solvents, and want to preserve my lungs and what is left of my brain for as long as possible :), also I would find it advantageous to market the finish used as 'safe'.Will shellac go on over an oil finish and stick?Is it possible to get REAL turps anymore, not the synthetic and presumably petroleum based stuff?Dano and Howard..........thanks also
*Gretchen,i All varnishes contain "plastic" of some type. The resins are generally alkyd, phenolic or some other "plastic". Howard's is not an assertion, it is fact. Yes, varnish has been around longer than "plastic" has. Shellac, lacquer, enamel have been in use far longer than varnish.The confusion is where one thinks of plastic in generic terms, "plastic" is a catchall word. Lexan, which is actually a poloycarbonate, is a type of plastic. Fiber glass, visquine, polypropolyne, vinyl, etc, etc, are all a plastic of some sort. Polyurethane is a type of resin. As the word "plastic" is used in a general sense, the way all varnishes are formulated today, they too could fall under the general heading of "plastic".As to depth of grain, that results from the number of coats that are applied. Wiping varnishes are not formulated to have high build, they are formulated to give the piece the appearance of a penetrating finish with the durability of a film finish.AJ, bottom line really comes down to what the health concerns one has, what look they are trying to achieve, and durability issues (if any) for that particular piece. Concerning health issues, as Dave alluded to, up here in the States, manufactures are required by Federal law to list toxic ingredients. So it is fairly easy of one to choose a finish in that regard. Maybe you can share with us what the laws are down under pertaining to ingredient listings.DanoAJ, I see you and I were posting at about the same time, as I believe I stated, shellac can be used over any finsih, that would include oil. Bulls Eye can go over polyurethane as well. As to real turpentine and it's availability, I don't know.
*Well, as to ingredients listings. coupla days ago I went to the local hardware to look at tins of finish. They had 'Scandinavian Teak Oil', 'Danish Oil', 'Polyurethane', and various urethanes with stains, some as a gel etc. What none had was a list of ingredients. The bes they could do was to give instructions like...." do not swallow", "in case of emegency get your a#*e to hospital" etc etc. not really much use.I may make some calls next week, ( is Saturday here ) and find out what the regs are with this. You can see now why it is so hard to identify one thing over another here, and my confusion.I will still have a go at making my own brew. At the very least it will minimise the amount of solvent present in it.
*AJ,As I hinted at earlier, it is a very competitive industry. Each manufacturer has their own "secret reciepe". So one does have to be careful when explaining formulations.Dano
*Howard,I see I must have been posting while you had already posted, didn't see your post. If I may, there used to be a distinction between "varnish" and "spar varnish" and this would be in part by the resins. A "varnish" would apply to an interior varnish using the resins you mention. "Spar varnish" would apply to varnish used primarily for marine use, where pine sap was the primary resin used because of severe wood movement issues in regard to moisture as well as created by streses. So, a high quality marine grade varnish will never fully cure, it has to remain flexible. The "resin" is one of the primary hardening agents. As to "all natural" varnishes, while I am not aware of any being marketed, there are certainly those who formulate their own, luthiers and violin makers to mention just a couple.Gretchen, sorry if it appeared that I was "piling on", that was not the case.Dano
*AJ'Real' turpentine was available in Oz -- practically any hardware store had it in 250ml, I used to buy mine in a tradesmans paint store in 4 litres, so I would think you'll find it in NZ. For my waxes I used an electric fry-pan in which I melted beeswax cake and when it was liquid, poured it into a container and added the same quantity of pure turpentine. It needs stirring from time to time as it cools -- colour can be added if necessary at this stage. This was applied over the penetrative oil finish. The feature with Rimu that I found so astounding was that there was this biscuit-colour timber -- bit boring really, and as soon as the oil hits it WOW!-- it looked as though you were painting the floor with walnut stain!
*Will add my 2 cents here regarding poly varnish. I did a cherry hutch top using Deft brand high gloss poly. I thinned it 50% with paint thinner and hand rubbed each coat. After each coat dried for maybe 10 minutes I would lightly wipe smooth with cheese cloth dampened with thinner. After 2 or 3 hours or more I would buff with a buffer. I repeated this process maybe 10 times. It turned out to be the best finish job I have ever done. Before starting the finishing, I had sanded ending with 600 grit w/d paper and paint thinner.
*Ian, thanks. I will have a look round for some real turps. I got some 'ordinary' turps the other day and some boiled linseed oil, and made up some thinned down stuff. will get hold of some 'carnauba' wax too for the brew.When I went to the hardware shop for the linseed etc, I asked if they had wax. reply was 'no, what do you want it for?'. I told the attendant and she said 'what about melted candle wax?'.............somehow I dont think so.then she suggested a pre made wax product which comes in various colours. not want I want so I declined. Whilst showing me the stuff, she said .......'its got toluene in it', as if to say 'this is a good thing to have....' Just to make sure I heard right I looked at the can, sure enough in fat capitals on the lid 'contains TOLUENE'. I know enough to know that this stuff is seriously toxic. Is such a thing really necessary in a wax? Needless to say I will be avoiding it.Do any of you avoid some products because it includes toxic ingredients?On the subject of shellac.......if it can adhere to an oiled surface it must be something else. I mean, not too many things will right?
*AJ,I'm not being sarcastic but, if I avoided products because they are toxic I would be limited to beeswax.I do take the necessary precautions, though.As to shellac, maybe you need to be a little more specific about "oil". When I think of "oiled" finish I think of boiled linseed or tung oil. Shellac will cover them both.Dano
*I was referring to linseed and tung. still amazes me how it can stick. Shellac is dissolved in alcohol, oil needs turps etc to thin, alcohol wont work, so how can these 2 apparently incompatible finishes stick to each other?I know your not being sarcastic, as I know that many finishes are toxic one way or another, but to me there are limits, despite the req. precautions being taken. Due to its severely toxic nature I think Toluene is way too much, so its inclusion in a product puts it on the 'no' list for me.
*AJ,Can't really answer the question as to why it does cover oiled finishes. In a previous post above, I mentioned how boiled linseed oil really "pops" the grain of Cherry. I often times will do this, let dry for about a week and use shellac as the final finish, the degree of depth that I want determines the number of coats I put on. I suppose that this is one of the reasons why I like shellac so much, pretty versatile stuff.Dano
*AJ, I don't think Carnuba wax is that much harder than beeswax that I'd bother to use it -- as for candle-wax (or parafin wax in Britspeak) again it's not harder. I bought all my beeswax straight from an apiarist and I paid $A25 for 2 litres -- much cheaper, as I couldn't find it in any trade stores except as made up polish. If you need to colour it then universal paint stainers will do the trick.
*AJ, if you were in the U.S., I would bet the wax product you were shown was Briwax. I believe its the only one here with toluene in it. It is prized by the antique crowd because the toluene will cut through most grime without damaging an old finish. Using it on many new finishes is a serious mistake, as it will damage a partially cured finish.Shellac is "sticky". It will bond to most anything that's cured.Ian, I'm unhappy to disagree with you, but Carnauba is seriously harder than beeswax. A solid block of beeswax I can easily mark with my fingernail, Carnauba not so. Whether it makes any difference in use is a different story, though.Dave
*Dave,You're correct, my point should have been that beeswax would be hard enough and considering the price of carnauba wax, more cost effective.For floors (probably a harder wear area than furniture) certainly beeswax is hard enough and it hardens with age. I had to extend an oak parquet floor once in the 150 year old chapel of a convent and the wax finish on it was like glass!
*TABsorry dude, ya aint geting any money outa me. not that I'm mean, I just dont have any!the wax was Briwax too. I am just going to avoid it.Yes we do have respirators with good filters here. Geeze this isnt Australia ya know!thank you all for you input. I now have a pretty good understanding of all this and willmake up a 'brew' myself. never know...........might even be able to sell it. :)
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