Different finish inside and out

Discussion in 'Woodturning Discussion Forum' started by Robin Thompson, Nov 4, 2017.

  1. Robin Thompson

    Robin Thompson

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    I have just finished turning a red oak bowl as per customer request. This bowl is meant to be functional as well as aesthetically pleasing. The inside of the bowl will be kept natural color whereas the exterior will be dyed with alcohol based dye then the pores filled with a metallic cream filler. I would like your thoughts and or suggestions in regards to applying a top coat to the bowl. I have always, up to this point, finished all my turnings inside and out with the same product considering food safe etc.. I am intentionally not going to elaborate on what finish I am thinking of applying so I get a broader range of options and or opinions. I hope I haven't confused you all and feel free to tell me if I have.
    Rob
     
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  2. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Clear gloss lacquer is what I would use. Since it is very ring porous, red oak isn't a very good wood for soup or salad so I am assuming that it will be used to hold something else that isn't liquid. I like your plan to use dye and metallic paste. It's a beautiful combination. One suggestion that I offer is to shoot a coat of lacquer over the dye before filling the grain with the metallic paste. You don't need to be considered about the lacquer filling the pores, because that is not going to happen with red oak.

    Something else to think about is color. Because aniline dyes are transparent and the color of red oak being mainly a mixture of red and yellow, the final result of subtractive coloration will be significantly different than the color of the dye, especially with blue dye. You can significantly counteract color shifting by bleaching the wood with two-part wood bleach that consists of sodium hydroxide (lye) and a strong solution of hydrogen peroxide (30%). Finish turn and sand the exterior before bleaching, but wait until after the bleaching is done before turning the inside if you want it to remain natural.
     
  3. hockenbery

    hockenbery AAW Advisor Staff Member

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    A major consideration in your plan is that the dye will run through any unsealed pores to color inside surface. Sanding will clean off the surface but the pores will be colored dots.
    Finishes like watco would also use the pore highway,

    You could seal the inside with a coat of lacquer, color and finish the outside, sand the inside and then finish the inside with a Mahoneys oil or whatever since you will have sealed the pores on the outside.

    Two issues are Red oak can’t be sanded too hard or the softer part of the grain line will erode making tacile grain lines and the unsealed pores on the inside will get dark with use.
     
    Last edited: Nov 4, 2017
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  4. Gerald Lawrence

    Gerald Lawrence

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    I have a pecan piece I have done with Chestnut stain in Royal Blue on the outside with gold gilt cream over that. Had wondered will lacquer affect the gilt?
     
  5. Robin Thompson

    Robin Thompson

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    "sodium hydroxide (lye) and a strong solution of hydrogen peroxide (30%)"
    Bill, when you say a strong solution of hydrogen peroxide (30%,) do you mean the % of peroxide in the mix is 30% or the strength of peroxide is 30%?
    I wouldn't know where to buy peroxide that is anymore than say 3% like the typical drug store variety.
     
  6. Robin Thompson

    Robin Thompson

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    Gerald, from what I have read lacquer will not affect the gilt. Mind you, I have never tried it.
     
  7. Robin Thompson

    Robin Thompson

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    By lacquering the interior (actually I use post catalyzed conversion varnish) does that prevent the dye from coming through the walls of the bowl?
     
  8. stu senator

    stu senator

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    Have you any samples of the wood that you can cut to thickness, both end and face grain, and try some samples of finish?

    Stu
     
  9. Robin Thompson

    Robin Thompson

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    Stu,
    I think that is what I need to do. As Bill stated, "Because aniline dyes are transparent and the color of red oak being mainly a mixture of red and yellow, the final result of subtractive coloration will be significantly different than the color of the dye, especially with blue dye." To be honest I had not really considered this. I have dyed a lot of wood but not red oak. I expect he is 100% correct. Sampling might be best.
     
  10. Bill Boehme

    Bill Boehme Administrator Staff Member

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    AI, I haven't dyed red oak because I prefer using lighter colored woods for dyeing, but I agree that the open pores pose a problem if dyeing only one side. I have successfully dyed one surface of white ash which has open pores by using the dyeing technique demonstrated by Jimmy Clewes. He uses a piece of folded paper towel and lightly wets it with dye and then wipes the surface in quick light strokes so that the dye can't penetrate much beyond the surface. This might prevent the piping problem you described.

    I also use Jimmy's method of wetting the surface with alcohol and then igniting it to burn the alcohol off and raise the grain before dyeing. I don't know if the heat treatment helps to reduce piping, but it might. Also sealing the inside surface prior to dyeing the outside might also help.

    The wall thickness is another important consideration. Doing this on a thin walled bowl would be a problem. If the walls are ½" thick or more I think that the problem can be avoided.

    It's always best to try something new on a practice piece of wood before using it on the real deal.
     
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  11. hockenbery

    hockenbery AAW Advisor Staff Member

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    I have never dyed red oak but every piece I have wiped with finish bled through to the other side.

    There are lots of variables with Dye. Thin pieces tend to send dye through to the other side more than thick pieces. Dabbing the dye on would reduce the likelihood of getting a dye to run through a pore. However if you spritz it with a alcohol mist that would likely carry dye through a pore to the other side.

    One issue I have had with Camphor hollow forms and dye is that airbrushing black leather dye inside tends to darken surface objects dyed another color. Just takes a little of the brightness away. Airbrushing acrylics does not bleed through. Camphor is not real tight grain but it colors nicely with spirit stains.
     
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  12. Bill Boehme

    Bill Boehme Administrator Staff Member

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    There are two products Baquacil Shock Oxidizer and Aqua Silk Shock Oxidizer that are both 27%. They are swimming pool chemicals. There are other types of shock oxidizers that are chlorine based and not suitable for bleaching the pigments in wood. Here is a link to a tutorial on bleaching wood.
     
  13. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I've used lacquer over several different types of metallic pastes and it is great. I would be more concerned if the finish was a slower drying varnish.

    The reason for applying lacquer over the dye before using the paste filler is to make it easier to buff off the metallic paste from the surface leaving it only in the pores. At least, that's my preference.

    I've also made some pieces where I first applied silver Rub 'n Buff onto bare wood and then rubbed off as much as I could and then buff it to bring it to a metallic shine. I then wiped Chestnut dye over the surface and let it dry. Next, I very lightly misted the surface with alcohol. Be careful, too much an it ruins the results. The alcohol misting gives the dyed surface a reticulated appearance. This seems to work best on gnarly and cracked white oak because the figure telegraphs through the finish. The only picture I have was done on a maple bowl ... OK, but not as interesting.

    Maple Bowl

    [​IMG]


    One other thought about practicing on scrap wood ... Make a small bowl out of the scrap because you want to see how this works on all grain orientations, not just side grain. The biggest area of concern is end grain.
     
  14. Gerald Lawrence

    Gerald Lawrence

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    There is another that can be purchased at beauty supply houses, I do not recall the name
     
  15. Bill Boehme

    Bill Boehme Administrator Staff Member

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    It's now sold as "developer" in the beauty industry and its concentration, rather than being stated in percentage hydrogen peroxide is now given by the term "volume". 10 Volume developer (also called V10) is 3% hydrogen peroxide. V20 = 6%, V30 = 9%, and V40 = 12%, so this is strong enough for hair bleaching, but far less than the shock oxidizer used in pools. To make matters worse, the "developer" products contains all sorts of other ingredients such as phosphoric acid and things to make it smell nice, etc. Not surprisingly, being a beauty product, it has a price tag to properly suit its purpose. Besides, my hair is already silver. :D
     
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  16. Robin Thompson

    Robin Thompson

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    OK, so I read up on bleaching wood at the link you provided Bill. It sounds like it would do the job but at the same time the hazard aspect of working with the chemicals scares the heck out of me. In the meantime I turned a small red oak bowl, sanded it to 220 then applied a light coat of red dye with a paper towel then lit it up. After the alcohol flashed off, I hit it with another light coat of dye and flashed that off. Surprise! It looked great. I then cut the thing into pieces to check the dye penetration. From all the cuts I made it appears the dye only penetrated about 1/32." Now I think I will proceed in this manner on the project bowl. I gave this bowl a coat of lacquer on the inside that will be dry by morning and I will put the dye to the exterior without bleaching. We shall see.
     
  17. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Red is fine. Blue will become green. If you want green then that would be the way to go.

    I put all the warnings there because I know that there are people who ignore instructions and and are far too careless with chemicals. The most important part of dissolving the lye crystals in water is to add the crystals to the water and not add water to the crystals. It's an exothermic reaction (meaning that heat is released) so the crystals need to be added a little bit at a time and stir to dissolve the crystals and then repeat until all of the crystals have been added. Wearing rubber gloves and a face shield are essential in case of a spil or splash or something is dropped. I've never spilled or splashed these chemicals on myself, but that doesn't mean that I won't. A little precaution doesn't cost anything except a little extra time.
     
  18. Fadi Zeidan

    Fadi Zeidan

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  19. Robin Thompson

    Robin Thompson

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    Thanks for posting Fadi. I watched the entire video. I suppose if one follows the safety precautions the end product is worth the effort. I'll think on it for a while.
     
  20. Bill Boehme

    Bill Boehme Administrator Staff Member

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    They say that beauty is only skin deep and this also applies to bleaching as well so do all of your sanding before bleaching. After the wood has been bleached and dried you can do a little very light sanding to remove raised grain, but if you do any more sanding than that you risk exposing unbleached wood.

    Bleaching box elder produces dramatic results. The tan areas become nearly snow white and the red is much more vivid, going from dull orangish-red or brownish-pink to a bright magenta-red. How can it be that bleach actually brightens the red you might ask?

    First, the simple answer ... let's think of bleaching box elder as the inverse of dyeing wood where subtractive coloration determines the final result. If we applied a magenta colored dye to wood that is tan or light brown, the result will be a duller orangish-red. Bleaching removes the color of the wood, but not the red stain.

    The slightly more complex answer involves wood chemistry and color science. Wood consists mainly of lignocellulose which is essentially colorless and a variety of organic extractives that reside mainly in the lumens. Some of these extractives are responsible for the colors in wood. The two-part bleach reacts with these organic extractives to remove much of the color. The bleach doesn't react with the red stain so the end result of bleaching box elder is that we are seeing the true color of the red when it is no longer the mixture of red and the wood extractives.

    There's more than one way to skin a cat . . . . uh, use two-part bleach. Some people mix the two chemicals together before applying them to the wood. I prefer applying the sodium hydroxide to the wood and then applying the hydrogen peroxide. I feel like this produces a much more vigorous reaction with a better end result. The downside is that it is messier. The messy part doesn't bother me because I do my bleaching in my garden. I also rinse the wood with a garden hose so that there aren't any chemical residues remaining on the surface. I then dry the wood with a towel and let it finish drying in the sun.

    Some people have expressed concerns about wood movement problems arising from getting the wood wet, however, we're talking about the wood being wet for only a few minutes so the wetness is essentially just superficial. Moisture penetration on end grain of box elder goes a little deeper, but what gets wet fast also dries fast. The biggest issue is a little grain raising. If you address grain raising before bleaching it will minimize raised grain during bleaching.
     

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