Spots in Toner Coat

      A finisher asks for help with a spotty toner finish. Will a thinner application solve the problem? July 11, 2005

I am looking for some help with a problem that Iím having and I can give some background on my setup first. I am using Fhure 350 HV for the finish and mixing their universal stain as a toner, with a ratio 16 oz of finish to 2 oz of stain.

I sand to 180, spray one coat of sanding sealer Fhure 360, sand to 220, and put on the tone finish. I am spraying with an Asturo BBS with a 1.7 tip at 20 PSI with the gun. Wet mill is between 3-5 mill for sure. I have an inline air and water filter before the regulator. The gun is clean and the pattern is good.

Now for the problem: With the first coat of toned finish I have a lot of that have water or wax left on the surface. I donít use serrated sandpaper, and the filter captures the water. Any ideas would be greatly appreciated. Iíve included a picture if it helps.

Click here for full size image

Forum Responses
(Finishing Forum)
From Paul Snyder, forum technical advisor:
I can tell you how to avoid the problem. Kick up the air a little (23-25 PSI), turn down the fluid, back the spray gun away from the surface an extra inch or two, and spray as thin a wet coat as you can. It may also help to reduce the stain by half (I'd normally use 2 ounces of stain per quart).

Spraying a normal full wet coat allows the finish to pool and puddle as well as penetrate any pin-holes in the sealer, and the color in the toner shows those imperfections drastically. By spraying as thin a coat as possible, the toner/color will not pool or puddle or seep into pin holes. If needed, spray more than one coat of toner to build the color you want (I always try to stick with one toner coat to make life easier).

From contributor M:
Can you explain more about the dots - are these tiny solidified particles, craters, or pinholes? Also, after you add the colorant into the coating, do you thoroughly mix, and then double strain the toner?

From the original questioner:
Paul, I tried what you have described, but a little different. I have turned up the air, but I didnít turn down the fluid. (By the way, my gun is a gravity fed.) I have also pulled away from the surface about 2 inches and sped up my pass speed a little. This has been an improvement, but I think I will have to reduce the amount of stain that I am mixing to the finish. For sure, the two different products will act different.

Contributor M - The spots do not have any texture to them. When I put my finger over them you could not tell that there was anything there. I do mix well and strain my finish/toner with a 190-micron filter from Gerson. The stain that I am using is a dye base and mixes well, so I have not been double straining. When I try another batch I will defiantly strain twice.

From contributor M:
It sounds like there might be some separation between the stain and the coating. There is no color in the dots, that I can see. You might want to give this a try: Add a small amount of the right compatible solvent into the stain, then thoroughly mix the stain, then add it into the coating, and mix it again.

From Paul Snyder, forum technical advisor:
To the original questioner: The key is to lay down a wet coat that's so thin it won't move around. That will keep the color coat even, and avoid the various problems that a full wet coat can produce.

By moving faster, you're basically doing the same thing as turning the fluid down; getting less fluid on the surface. If you can control it well, it'll speed up the process and achieve the same result. Basically, your goal is to just "fog" the toner on enough to wet the surface evenly. Don't sand the toner and apply a coat or two of clear over it for protection.

From the original questioner:
I am going to mix another batch of toner with half of what I used before for color. Like you said Paul, just fog it on and that seems to work better. As for mixing a compatible solvent to the stain first (witch is water), I am hoping that a reduction in the finish-to-stain ratio will be sufficient. The thing is, the finish and stains are supposedly compatible, I may have just pushed it too far.

From contributor S:
Are the centers of these spots showing a dry look? If so, you have contamination somewhere. Mix your blend of toner and pour it down a clean piece of flat glass and see if it separates on glass. If so, it is the product. If not, there is either something in the equipment, on the wood, or in the application process somewhere.

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