Final coat of Arm-R-Seal Topcoat keeps streaking

[Scott Jashinski]

I am using General Finishes Arm-R-Seal Oil and Urethane topcoat. Worked great for the first two coats. Now that I am trying to apply the third coat, it keeps streaking. I am using a rag and used very light pressure. That is not work out well. The coating became tacky very quickly and the streaks were terrible. I sanded that off and tried again with using a little more topcot but while it is a little better, I still see the streaks. I went slowly and worked in small sections and the overlap areas are really bad.

I need some suggestions/thoughts on what I am doing wrong. The piece is a 14" x 5ft piece of cherry.

Starting to get really frustrated so any help would be appreciated.

[therick34]

A few thoughts...

- I've used multiple gallons of Arm-R-Seal over the years and have never found it to be "finished" after three coats, regardless of what the can suggests. The last cherry top I did with Arm-R-Seal was around 5-6 coats before I considered it finished.
- Make sure the previous coat is completely dry before putting on the next coat as the tacking issue you're encountering can occur if it's not dry enough.
- Try a good quality foam brush instead of the rag. I'm convinced something has changed in their formulation over the last few years since I had never run into the streak/tack issue in the past, but I'm using it on a current project and had the same problems on the middle coats when using a rag, but it improved significantly after switching over to a foam brush.

Good luck.

Rick

[jteneyck]

If it's getting tacky you aren't putting it on fast enough or not heavy enough, or both. I have good luck on all but very large surfaces using a folded paper towel. Get it wet but not dripping. Wipe from one end to the other, reloading only if you have to. When you get to the end reload and take another swipe, overlapping your first swipe by about 1/3. Repeat until done. Don't go back over what you've already done no matter the urge to do so. If you've put it on heavy enough, the little imperfections will disappear as the finish flows out. If you try to go back over it the risk goes up that it will tack up and that's when you get streaks.

On very large surfaces I have to use a foam brush to get it on heavy enough and fast enough so it can flow out before it sets up. There's no harm in using a brush on smaller surfaces, I just prefer a paper towel.

It's harder to apply uniformly the higher the temp and the lower the RH. If you have a choice apply it when it's cool and more humid. It will take longer to dry, but you can't have everything.

How many coats you need depends on a lot of things. 3 coats are often enough, but sometimes it takes 5 or 6. When you have a smooth, uniform film you have enough coats.

John

Oh yeah, I almost forgot. You can increase the open time by adding some mineral spirits to ARS. I had no luck on a big table top once until I added about 25% MS. Then it went on easy peasy with a foam brush.

John

[Scott Jashinski]

Rick and Jim,

Thanks. Looks like I am off to get a good quality foam brush and wait until tomorrow for the next coat. I may also need more coats,

Do you typically sand between the coats? I've been using a sanding pad but wonder if that is necessary.

[jteneyck]

Yes, I sand between every coat, generally by hand with 400 or 600 grit on a foam pad.  I have used my ROS on rare occasions when I had some obvious defects on a large surface that would have continued to show no matter how many additional coats I applied.   

I you apply each new coat as soon as you can scuff sand by hand then it will bond better to the prior coat; essentially burning in.  This can be important if you intend to rub out the finish, greatly reducing the chance of getting witness lines if you cut through the top coat during the process.  

John

[therick34]

I never used to sand between coats of Arm-R-Seal, but I have needed to scuff between each coat on this one. The tops I'm doing now are pretty big (25x80 is the largest) and I've had some finish quality issues where I've never experienced them before. I'm building the base coat with semi gloss and will be finishing with satin, so we'll see how it ends up. Not sure that I'm as excited about Arm-R-Seal as I was previously -- it had been a while (I spray water based lacquer on 90+ percent of my projects) and I think I may start to avoid it. I got spoiled with 20-30 minutes between coats on the lacquer.

Rick

[Scott Jashinski]

So you ready for this.......turns out it was my tack cloth.


I went to Woodcraft to pick up some foam brushes and happen to run into the gentleman who teaches a finishing class and uses GF most of the time. As I took him through what I was doing nothing was apparent until he asked what I was using to wipe off the dust. I told him a tack cloth. He asked dry or sticky. I told him sticky. Apparently, whatever makes it sticky also interacts with the GF and would not let the finish adhere to previous coat. He stated it is even worse with water based finishes.

Got the brushes, sanded and wiped with a lint-free dry cloth and applied the finish and guess what....no more streaks. Could have been using the foam brush as opposed to the rag, but my guess is it was the tack cloth. Needs one more coat to really cover the previous issues but looking good.

He also recommended a technique where he waits until the finish just starts to dry and wipes the excess off with a cotton cloth. I will try that on a much smaller project.

Thanks for the help and though I would pass that along in-case other are not aware of this potential issue.

[jteneyck]

I never use tack cloths and I've had streaks, so I doubt that was the root of your problem.  More likely it was your application technique. 

john

[zaret]

i've found that a terrycloth/foam staining pad, wet with mineral spirits and then rung out, is an excellent way to apply arm-r-seal on large surfaces.  between coats i lightly wipe with the 320 or 400 foam squares (festool).

good luck with your project,

--- dz