|Forum topic by CharlesNeil||posted 05-15-2010 06:19 PM||1346 views||7 times favorited||5 replies|
05-15-2010 06:19 PM
Ok , since we have been having alot of finish issue threads. and hopefully helping to conquer them here is another… the term is “like on Like” in the industry , and from what I can see water base is surely going to be the finish of the future, alot of States already have so many VOC restrictions , our beloved oils and lacquers are going to have a tough time, not to mention the hazards they have… and besides Water base is a huge issue,, I have been deeply involved in it for 3 or 4 years now.. it has sure come along way.. however it does pose a significant problem, especially for the wipe, brush guys.. and even the spray guys, the issue is color migration and pull off , this happens when you have a like on like product, and example is a water base dye or stain, try to do a second coat, and it dissolves the first.. use alcohol base dye , use shellac or lacquer on a brush or wipe and the same thing, here is a past and copy from a good and pretty sharp guy on the issue
My friend Sal Marino , like myself has been around the block a time or 40 , here is a article he wrote some time back on compatability , its as true todayas it was then, but now we have issues as we look to use like substances… compatability in this case means not only that they work together but also one does not disturb the other.. here is Sal’s
I read today’s thread on the forum on “When the finishing dvd will come out” and your reply as to having to go back due to changes in product formulations as a result of VOC regs. Many years ago I wrote an article on topcoat finish/dye satin compatibility. You most likely know more on this subject than I do, especially since I have not been keeping up to date as much as you on the changes in product formulation.
The basis of my article was that solvent type, stain type and the type of solvent used in the finish all determine compatibility. Some of this info may no longer be accurate due to changes in product formulas, but it’s a good sound base of info regarding the problem in general.. I don’t know if this may be helpful to any of the readers but I have put together a summary in the event you may want to use it anywhere you wish.
1. Dyes – True dye powders completely dissolve in their appropriate solvent. Unlike pigmented stains, true dyes do not have any any binders or resins to lock in the color. If you apply a finish that contains the same solvent the dye was dissolved in, you will get some bleed back (even when spraying) of course not nearly as much as wiping or brushing the finish over the dye. Allowing the dye to dry for longer periods of time will not greatly reduce the amount of bleedback because as soon as the solvent in the finish comes in contact with the dye, it will start to re-activate, thus causing the bleedback and loss of color retention. The mechanical action of wiping or brushing worsens the bleedback.
Examples of soluble dyes:
Alcohol dyes =de-natured alcohol
Oil dyes = petroleum based solvents like turpentine, mineral spirits and naphtha
And of course water dyes =water.
Examples of incompatibility:
Water based finish over true water soluble dye
Oil based poly or varnish over true oil soluble dye
Shellac over true alcohol soluble dye
Examples of compatibility:
Shellac over water true soluble dye
Water based finish over true oil soluble dye
Water based finish over true alcohol soluble dye
Oil based finish over true water soluble dye
The bottom line is “if the finish contains the same solvent that the dye was dissolved in, you will have to deal with some bleedback and color retention problem, unless you first lock the color in with some type of sealer or wash coat finish that will be compatible with the dye prior to applying the finish that contains the same solvent as the dye.
2. Pigmented Stains – Unlike true dyes, pigmented stains contain binders, such as oils in oil based stains and small amounts of polymer resins in water based stains. Once applied and dry, these binders help to keep the pigment lodged in the pores of the wood and held on the surface. While solvent compatibility and color retention can still be somewhat of a problem when wiping or brushing finishes over these stains, the amount of bleedback should be much less than a dye, especially if the stain has dried properly.
Naturally, there are advantages in using both dyes and pigmented stains (which is an entirely different subject) however it’s important to have a good sound knowledge of just how dyes and pigments react to finishes.
foot note.. Google Sal if you want to know about him…
>>>>>>>>>> here is My fix<
the “like on Like” issue, we got it, I talked to chemist, after chemist, mixed, stirred, slopped, sprayed, wiped, brushed, nothing really worked… then I went back to the beginning, and my grass-roots and found the answer.. a 1/2 lb cut of amber shellac does 2 things, first it drastically reduces the migration and pull off second, it adds the amber tint that is a major issue with water base , problem solved… as far as I am concerned, I was determined to offer the hand guys a solution, spraying is the ultimate answer , but many just wont go there.. for various reasons, so the short answer is to the problem for the hand guys, is the same 1/2 lb cut, but you have to use a good natural hair brush and apply it wet and don’t over brush, you will still get a little pull off, but far less than wiping, you want just the tip of the brush to lay down a thin wet coat , after dry if you need to scuff sand it use a little 600 or finer and go very easy, you have very little film there, then rewipe with your stain or dye and move on, if you are going to brush a waterbase topcoat use a 1lb cut ,you want a heavier film, as the top coat will require more brushing to level.. it’s just how it is, spraying, is simple, again a thin wet coat of 1/2 lb amber shellac, ( dewaxed) apply stain or dye , and the 1 lb before the topcoat.. and its rock and roll… it sure sounds simple, and is, but it sure wasnt an easy find, I kept wiping the shellac, and it would pull color off, I tried adding finish to dyes to create a binder, adding more finish to stains to increase the binder , nothing worked… I knew the shellac was the answer, but how to get on without spraying, it’s again a fine natural hair brush, not the .39 cent ones at the box stores, get a good Purdy or Corona, they are not cheap , but its the key, also remember if you are applying water base any thing you want the reverse in a brush , you want a synthetic , NOT a natural hair, but for top coats, those foam brushes do pretty well, but again not for shellac, it will dissolve them