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02-24-2010 06:14 PM
OK, So I got through the pore fill and staining, looks good. I put my 2nd. coat of Behlens rock hard on this morning. I just checked on it and in indirect light I'm seeing brush strokes. I applied it across the grain as it stated on the can. Is this correct ?
If I sand lightly with 320 grit and give it another light coat will this help ? Maybe apply with the grain this time.
Also, it mentions waiting 72 hrs. for a rub out finish. How is that done ? Any suggestions or help would be greatly appreciated.
02-24-2010 06:56 PM
I think you mis-read the directions. They may have mentioned applying the finish cross grain, but they would have also mentioned spreading it and or tipping it off with the grain. It's a fairly traditional method to lay varnish on across the grain, BUT it is also part of the traditional method to spread and smooth the varnish with the grain. In addition, "tipping off" which is important, involves using your brush nearly dry and held almost vertically just lightly touch the surface (ie. kiss with the tip only) moving with the grain, to remove any surface imperfections like brush strokes.
Applied either direction you shouldn't have brush strokes anyway. Unfortunately, achieving that requires disregarding one of the label directions. The manufacturer will say not to thin the varnish. That's just not true. The maker's say that to carry through a fiction that they have limited the VOC's as required by regulators. That's not really true--they just must be added by the user, but the manufacturer can't say that. So you should add 10% thinner as a starting place. That will let the surface flow out.
From this point you should use a sanding block and sand with 320 grit so that the brush strokes are eliminated. That could be a bit more than lightly sanding, but take care not to cut through, particularly near edges. Then apply another coat with the thinned varnish, spreading it evenly and thinnly, and not forgetting tipping off with the grain.
Seventy two hours is a very minimum for rubbing out. You will generally be better off to give it several weeks or a month. That allows the varnish to become more fully cured and harder. Harder means easier to achieve an even sheen in the rubbing out process.
02-25-2010 03:20 AM - edited 02-25-2010 03:24 AM
…is not all that important if: 1) the varnish is properly thinned, and 2) you are using a proper varnish brush. While it is true that “tradition” dictates that varnish be tipped-off with the grain, and most instructions (including mine) make that point, if we consider the process we will see that grain direction and finish application are not related. Let me explain:
Finish is a liquid. If it is properly thinned it will flow-out and level itself. Finishes (again, properly thinned) don’t tend to stack-up; brush marks go away all by themselves. A trivial example would be a comparison between pulling a plow through soil vs. pulling the same plow through a pond. I have brushed varnish onto many projects where brushing with the grain was difficult to impossible. For example, a table apron to which veneer had been applied vertically. Brushing direction is far more a function of the structure being finished that the direction of the grain.
So, let’s focus on: 1) thinning, and 2) the nature of the brush. A good place to start is thinning on the order of 10%. But, that is not a rule; it is a guideline. Only by brushing on the varnish will you know if it has been properly thinned. By lighting your work surface with a low angle light you can easily see if your brush marks are leveling. If they are not then you must add a bit more thinner to your varnish. Tipping-off does not eliminate brush marks…remember, it is being done with a brush! You can’t eliminate brush marks with a brush any more than you can remove planer marks with a planer. The point of tipping of is to further spread the finish into a thin, uniformly deposited finish film. Finish leveling is accomplished by thinning (and assumes the use of an appropriate varnish brush).
A paint brush, even a very good paint brush, does not a varnish brush make! In the same article I linked to above I discuss what makes a good varnish brush. Perhaps the most important property is the ability of the reservoir to hold an adequate amount of finish so you are not constantly returning to your container for more varnish. (Remember, the objective is to apply thin, uniform coats, not a thick coating). That is easily determined by testing the ability of the brush to “wick” varnish into the brush by dipping just the very tip of the brush into a container of thinner.
In closing, I suspect that the brush-with-the-grain admonition has its basis in sanding with the grain. But, it is important to understand that sanding, even final sanding with fine grit, imparts scratches in the wood. Finish is applied on the wood. Finish will reveal scratches in the wood; but, if properly thinned and applied with a proper brush, finish (like any liquid) will flow-out and level itself. Liquids have no structure of their own.
02-25-2010 06:22 PM
Thanks for the replies and help Amateur and Steve.
After useing 320 grit and determined I would still be at it a week from now, I bit the bullet and got out the ROS. I got it down to bare wood and re-stained. It looks good.
I think the whole problem was not thinning the varnish. After reading the can again, " May be used at full strength, for better flow, may be reduced up to 25%. Apply thin coats across the grain, brushed level with the grain ". I don't understand the last part of that statement.
Now, should I start the thinning at 10% and add to it if need be for a better flow ?
Also, they sell their varnish reducer to do this but, couldn't I just use mineral spirits ?
Thanks again guys, George
02-25-2010 09:28 PM - edited 02-25-2010 09:29 PM
Behlen's has reduced the VOC's in recent years (EPA Regulations $%@#^!!) so thinning is a must...
thinning 50% makes it a wiping varnish the 25% limit on the can is either VOC regs or marketing guys.
It is better to use their thinner; for some reason, regular mineral sprits doesn't work as well in this varnish.
Finishing is an 'Art & a Science'. Actually, it is a process. You must understand the properties and tendencies of the finish you are using. You must know the proper steps and techniques, then you must execute them properly.
02-26-2010 03:33 AM - edited 02-26-2010 03:37 AM
…a much easier way to remove the brush marks and save the work you had already completed would have been to scrape the surface with a card-type cabinet scraper until the finish was uniformly dull. Then, apply your final coat. That aside, the instruction to “…brush level with the grain” simply means that your brushing technique should spread the varnish film in a thin, uniform coat across the surface of the wood.
Thinning 10% would be a good place to start; but, as I wrote in my original reply, it isn’t a rule; it is simply a guide line. The extent to which you thin the varnish is still a function of what you see as you brush it on. Again, use a low angle light source so you can see the surface and thin accordingly.
Behlen’s “reducer”, in my view, is just another way to get in your pocket. You can easily produce a functional equivalent in your shop and save the $10 to $12 retail cost. There are two prominent chemicals in Behlen Rock Hard Varnish Reducer as identified by the CAS number in the MSDS. They are CAS #64742-47-8 and CAS#64742-89-8. Both of these chemicals, according to the MSDS, make up between 30% and 50% of the “reducer”. When we search chemical data bases on these two CAS numbers we find two interesting synonyms. CAS #64742-47-8 is A.K.A. “Mineral Spirits”, and CAS #64742-89-8 is commonly known as Naphtha, Solvent Naphtha, or VM&P Naphtha. Other identified chemicals can best be described as “trace chemicals” found in the two prominent components Stated another way, Behlen reducer is nothing more complicated than a blend of mineral spirits/paint thinner and VM&P (Varnish Makers and Painters) Naphtha in more or less equal proportions. Behlen’s instruction to use their proprietary thinner is a classic example of uniqueness created by packaging, not content. Now, to your specific question; “…couldn’t I just use mineral spirits?” You can; but, to retain formulation compatibility you should use a 50/50 blend of MS/paint thinner and naphtha. It is this thinner “blend” that creates the 4-hours to tack-free property of the varnish. As an aside, it is also this blend that makes Behlen Rockhard difficult to thin and apply as a wipe-on varnish. The thinner flashes off too fast.
The most important thing for the user to understand is that Behlen defines this varnish as a “short-oil varnish”. Without attempting to determine precise content, this simply means that the amount of oil (linseed in this case) used to make the varnish is less than that used to make regular-oil or long-oil varnish. As a result the relative volume of resin is higher. It is this relationship between oil and resin (the “solids” in the varnish) that contributes to the relative “hardness” of the finish. It is also why thinning, and applying the varnish in thin coats is so important to achieve proper flow-out and leveling.
02-26-2010 05:58 PM
Thanks for the help everyone. I think I finally got it. I went 80/20 on the first coat and it made a world of difference. I'll give it a second coat tomorrow and see what happens, but I feel confident about the results. Thank Steve for the techniques article on application, it helped a lot.