Avoiding Runs with Waterbornes
A discussion of formulas, guns, and techniques to prevent drips and runs. June 30, 2009
Question
Is anyone out there using the setup with 255, and if so could you please tell me what tip size you are using and your settings for your air and fluid. Too much material is coming out so it causes runs. I am using a 12-094 tip size with fluid pressure at little less than 10 and my air at 20psi. Any tips on this would be great. I am using a Kremlin 20:25 pump.
Forum Responses
(Finishing Forum)
From contributor L:
Look below.
Kremlin Airmix Air
From contributor C:
When I first started using FUHR I used 255 for some time. I switched over to 250 and received better results. You may know this as well but it is basically the same just a higher viscosity product. I had the same issues with runs on vertical surfaces. I have since used 260 and now 345. The 250 and 260 cost a bit more and both are exterior grade as well. The 345 is a new product and has more of the look of the 260 and the feel of the 250. As for the spray guns I use the CAT Lynx HVLP. About 20lbs at the pot and 55 lbs of atomization air measured at the pot side of the line.
From contributor P:
I have a 10-14 pump and an MX gun, but have sprayed a lot of 255 very successfully with the 09-094+ tip. Fluid pressure is set at 30 and the air set so the tails just disappear. Remember to hold the gun 10 to 12 inches from the work, I had problems when holding it closer. It's a great combination. I wish the Fuhr was easier to get up here in Canada.
From contributor B:
I used both 250 and 255 for a while. I found the 255 to be a clearer finish but it has no real vertical hold. The 255 worked well but changes the color of the wood too much. We switched to Fuhr 380 Water clear acrylic varnish. It truly is water clear and it doesn't change the wood color at all. It’s very water resistant and almost submersible. I also have had absolutely no problems with bonding to the oily exotics. And yes you can use it on Purpleheart. The best rule of thumb is thinner is better. I can get you the tip size and the pressures I run on my Kremlin. The 380 has an exceptional bonding capacity. The only thing you really have to remember is not to sand too finely. I sand the wood to 180 and then seal with two coats of 380. Then I allow it to cure for at least 48 hours. This is not the recommended time, but I find it works better. Then I sand with 320. Usually I put two topcoats on in fairly rapid succession. About 20 minutes dry time between coats. It takes some practice but you can produce a pretty slick finish this way. I have recently started using the Fuhr stain retarder to help reduce the orange peeling.
From the original questioner:
Thanks for the tip. I was using 380 for a while but found the 255 feels the best meaning it feels like someone put a wax on it. Did you have any issues with 255 around water?
From contributor B:
We never had any problems with water on either the 250 or 255. When I was using the 255 I had the fluid set on about 60 and the air at 20-25. I know that seems high but it worked for me. The stuff we make has to be coated on both sides and the edges in a single shot. They hang on wires through the handle hole. You learn to move fast. I really was serious when I said thinner is better. One trick I learned was to spray on a very thin coat and let it just dry to the touch and then put on another coat. I had good success with this. You do need to be careful not to wait too long as the second coat won't bond if the first gets to dry.
From the original questioner:
To contributor B: do you think I should get a different tip? I noticed that there was a lot of material coming out and looked good when it dried but in some areas there were bubbles that looked like gas bubbles. I notice that you have to move fast or you use too much material in certain places and that's where these bubbles appear. Do you use your Kremlin to spray 380? If you do, what tip size works for you? I am using a 20:25 pump if that makes a difference. I am learning more each time I use it but it's always great to get good tips on better spray otherwise you waste a lot of material which can cost a lot.
From contributor C:
Something that happened to me when I used 255, I had the atomization air a bit too high. This was blowing bubbles into the material and looked like blisters. I lowered the air and that cleared up. Again I use Cat HVLP so the mix may be different. I too have been using 380 and yes it is clear and is a great product. I am trying the new 345 clear but it feels like more like 255 and 250. If you have not yet tried the 250, I did not have the bubbles with it. I push the air about 20 lbs more with 250, 260, 380 and 345.
From the original questioner:
W To contributor C: when you are using 345 are you doing all your coats in satin? If so, how does it look?
From contributor C:
Yes I use satin most times. I have only just started with the 345. I plan to finish a red oak kitchen (stain and seal coat). I just bought my 2nd (5 gal) I used up my existing 260 and 380 before. I used the first 5 on a natural birch plywood shelving job, but I like the look and feel. I have had very few issues. The blisters and the running with 255 I think for me the product temp weather are the other factors. Someone asked about the blush. I have not seen any at all, since it is water the conditions for blush are very different from solvent as well, even near non-existent.
From the original questioner:
What did you think of the 345 on the red oak? Have you use their stains on maple with success at all? I have tried a few different techniques and have not come up with a good solution.
From contributor C:
I use the 155 stain, they have a new stain out as well but I have not been able to really use it and so far I do have a sample. I am using up old inventory first. I buy stain by the 5 gal and it takes a while to use it up.
Yes I use the 155 on maple most times soft maple but have done hard as well. They also sell the stain base in clear for use as conditioner but I quit using it and just go directly on the raw wood. I try convincing the homeowner that maple does not work well in dark colors because of the blotchy spots show more in dark colors.
As for the 345 on oak so far I really like it. The viscosity seems to be more like 250 and 260 so it hangs in well and builds well. I sand a bit more than most shops. I have a drum sander, they are not as good as a wide belt for refining the sanding so I use a 100 grit random orbit and get the sanding scratches out and then 120-180-220 all random orbit - really just a couple of passes to lessen the grain raise. One thing I like is that 155 is a spray stain with wiping as optional so I can very easily stain the inside of the cabinets and not mask or cover anything. I have had several customers that commit about why so many shops do not stain the interior of the boxes due to the extra labor. With spray stain I see less labor and a nicer overall finish; I get a lot of good complements on my finish.
From the original questioner:
Any of you guys use their glaze with 255 on top of it. I have a job coming up and want to use 255 over the glaze but I was wondering if there will be any attachment issues?
From contributor C:
I used Fuhr glaze and 250 on one occasion a couple years ago, seems like the sealer was 360. As for adhesion, I did not have any issues at all. I have since been advised to use 380 for sealer. A side note the 380 cost less than the 360 sealer also. I stained the wood, put the seal coat on, scuffed, applied the glaze, slightly scuffed again and then 250 final coat,
I am a bit curious about your use of 255, don’t get me wrong. The 255 is a wonderful product, I am sold on 250 if you want the product for cabinets and are convinced. I too was sold for quite some time “exterior grade” and the waxed feel.
If I ever use 255/250 on another job I may use 255 for the seal coat and 250 for the top coat. The 255 will go deeper into the wood due to the viscosity. I always noted that the seal coat of 255 filled the grain so well and then the 255 for top coat was just too thin and that’s when you get the issues with vertical hold. I can very well see 255 for use on flooring and roll coating but for cabinets again I think you would be better served with another series. If you go with another such as 250/260/380/345 you will have to adjust your fluid and air mix to get the desired results.
