Festool Owners Group

GENERAL DISCUSSIONS => Finishing and Painting => Topic started by: mrFinpgh on January 24, 2021, 06:03 PM

Title: What is up with these streaks in my finish?
Post by: mrFinpgh on January 24, 2021, 06:03 PM
I'm making a bench out of cherry, with a curly cherry top.  After about 40 finish samples, I locked down a process that gets the color needed.

High level, the process is waterborne dye, 2 thin coats of shellac to lock it in, and about 4-6 coats Arm R Seal satin.  Dying cherry seems to go better after sanding to 400g. 

From some angles, it looks alright:

[attach=1]

[attach=2]

But from a sideways view or at a low reflected light, there are many visible streaks in the finish.

[attach=3]

[attach=4]

The first two coats of Arm R Seal, I laid it on pretty heavily and let it soak for about 8-10 minutes before wiping it off.  By the second coat, I was noticing streaks.  The next two I applied with a shop towel.  After this, I waited 2 days and did some block sanding with 600g paper.  This showed a lot of high/low spots. 

I've never had a problem with Arm R Seal in the past - having used it for a number of tables, trimwork, frames, etc..  Not sure why I'm running into an issue here or what the root cause might be.  Does anyone know what might be happening?

Title: Re: What is up with these streaks in my finish?
Post by: Tom Gensmer on January 24, 2021, 06:26 PM
The streaks are likely due to layering multiple layers of “Satin”. It is my understanding that all finishes are by default “Gloss”, with the lower sheens having varying amounts of particulate matter added.

The streaks are often clumped particulate created when brushed or wiped, and will only get worse.

In my experience, it’s best to build coats in “Gloss”, switching to “Satin” only in the final coat. The only time I did all layers in Satin was when I was trying to mimic a cloudy finish, and I applied via sprayer....

You will likely need to sand back to the shellac to get rid of the streaks. At that point, either build with Gloss, and/or apply with spray equipment. Hope this helps!
Title: Re: What is up with these streaks in my finish?
Post by: mrFinpgh on January 25, 2021, 06:34 PM
Thanks, Tom.  I hope that this isn't the case here -- I suspect it would be pretty tough to sand off the varnish without cutting through the color. I already had to do that once due to some uneven sanding causing striping.

I often see this wisdom of 'build with gloss and finish with satin'.  Yet Flexner says it doesn't matter and that you could put gloss over Satin and get less of a Satin sheen.  I've never really tried mixing approaches before, and it's always worked out okay.  On the other hand, I never really 'build' much with Arm R Seal so maybe it's something I wouldn't notice.

I'm going to ask General Finishes themselves before I break out the Rotex. 
Title: Re: What is up with these streaks in my finish?
Post by: RobS888 on January 26, 2021, 09:25 AM
"The first two coats of Arm R Seal, I laid it on pretty heavily and let it soak for about 8-10 minutes before wiping it off. "

I have never wiped off Arm r seal. I can't imagine why you would want to. I lay it on and then let it self level.  I think you may be pulling the partially setup coat of Arm-r seal when you are wiping it off.

I have put on nine coats of Arm-r-seal and it never does that.
Title: Re: What is up with these streaks in my finish?
Post by: grbmds on January 26, 2021, 10:40 AM
If you go to General's site there is are great videos which show the recommended methods for applying their various finishes. The video for Arm-R-Seal shows 3 ways to apply involving cloth, a terry cloth sponge, or a paint pad covered with a cloth. None of them indicate waiting any period of time between application and wiping off the excess. The excess is wiped off immediately after the entire surface has been covered with Arm-R-Seal. Although I'm not an expert on Arm-R-Seal, I suspect that the wait was the problem. By the time you started to wipe the surface some of it had already dried and the areas where there was excess hadn't dried. I think that would give you an uneven finish. If that is the case, I would try sanding the surface lightly with 320 or 400 grit paper (most likely by hand with a sanding block), vacuuming and wiping it down to remove the dust, then applying another coat as General indicates on their site, is likely to get rid of the problem. It may require doing this process twice. Once a finish starts to dry, I have found that it is very difficult to get the smooth surface desired when wiping it. Given the consistency of Arm-R-Seal, I would assume that it would be self-leveling once the excess is lightly wiped off before it dries. Any minor imperfections could be eliminated in subsequent coats.

I would add, I'm just guessing, but you could contact General. I think they would be responsive assuming that their staff is available for support during the Pandemic.
Title: Re: What is up with these streaks in my finish?
Post by: RobS888 on January 26, 2021, 04:10 PM
The beginning of the videos says it is the 3rd coat in all videos.

I put a liberal amount on with a foam brush and smooth it with the foam brush lightly held at a flat angle. Levels itself nicely.
 
Title: Re: What is up with these streaks in my finish?
Post by: mrFinpgh on January 27, 2021, 11:59 PM
"The first two coats of Arm R Seal, I laid it on pretty heavily and let it soak for about 8-10 minutes before wiping it off. "

I have never wiped off Arm r seal. I can't imagine why you would want to. I lay it on and then let it self level.  I think you may be pulling the partially setup coat of Arm-r seal when you are wiping it off.

I have put on nine coats of Arm-r-seal and it never does that.

It's a technique I learned about from Darrell Peart.. he used to use Arm R Seal Satin on his pieces before he switched to Livos.

I've tried to reach out to GF but nowadays they route everyone to their facebook group, and the support is not great.

I did some sanding over the past few evenings to try and improve things..  600g had some corning and was leaving scratches, so I dropped to a 400 disc.. that seemed to be leaving a less consistent scratch pattern too, so I dropped to a used 320 sanding pad. I was able to get to a pretty uniform dullness but some spots seem to be showing signs of cutting through already.  I can do some touchup with tinted shellac between coats, but I don't want to have to do a lot of that if I can avoid it.

I did watch the videos on their website, where the guy is applying it in broad circles before doing a final wipe with the grain to even it up.  Hard to tell exactly how much he leaves on there, but he insists it isn't much. I think the challenge in that approach is knowing how much to put on the surface before you clean it up.
Title: Re: What is up with these streaks in my finish?
Post by: grbmds on January 30, 2021, 05:20 PM
I would suggest that, between coats, you hand sand with paper around a block rather than use a random orbit (that's what it sounded like you were using). Random orbits between coats is too aggressive. I know I have more control hand sanding because I can just lightly sand which you really can't do with a sander.

I would think that, if you hand sanded lightly and coated it with another coat just like General says in their video, it would at least improve, if not go away. Wiping off at the end is meant to get rid of brush marks and any excess. The remaining will level out. At least that has been my experience with almost any poly like General's.
Title: Re: What is up with these streaks in my finish?
Post by: mrFinpgh on March 14, 2021, 02:37 PM
Hey guys,

Thanks for all the comments.  I think a few things were going wrong for me:

1. I think I was laying down too much finish - to the point that it was puddling instead of leveling out.  It didn't seem like a lot, but apparently it was enough.

2. I was doing a back/forth stroke and this may have been overworking things.  With overlaps, that meant sections were being hit four times with some delay between them, given the size of the piece.

3. I suspect my shellac sealer might be making things worse.  I didn't adequately scuff and I think those ridges were creating a persistent issue at the foundation of the finish.

4. As some folks mentioned, building a finish with Satin may be a bit of a problem. I think that the flattener do present a challenge if you aren't careful and even GF suggests building w/ gloss or semi gloss.

So I did some sanding and scraping to remove all the finish off the top of the piece, then I resanded back to 400, raised the grain again, dewhiskered that, and reapplied my dye mix.  I was really worried about losing the curly figure since I had already soaked the piece w/ arm r seal previously - my concern being that the end grain would be sealed up too much and not absorb like it needed to for the curl to work. Applied some shellac and have started to do some build w/ gloss Arm R Seal. I think this is 3 or 4 wiped on coats.

Here's where it is today, with sun coming in from behind it.  It's very shiny, and less obvious streaks, but it does have a bit of a rippled effect. I'm not sure why that is - maybe this is the normal for gloss wiping varnish?

[attach=1]

[attach=2]


My intention is to rub it out to a satin sheen like the rest of the bench - a new experience for me.  Usually I have just used Satin Arm R Seal but I think the size of the top is partially responsible for the challenges I've been having with it.

Those folks experienced w/ Arm R Seal Gloss - am I on the right track?  Or should I be trying to do something different here?

Thanks,
Adam
Title: Re: What is up with these streaks in my finish?
Post by: Crazyraceguy on March 14, 2021, 03:16 PM

I often see this wisdom of 'build with gloss and finish with satin'.  Yet Flexner says it doesn't matter and that you could put gloss over Satin and get less of a Satin sheen.  I've never really tried mixing approaches before, and it's always worked out okay.  On the other hand, I never really 'build' much with Arm R Seal so maybe it's something I wouldn't notice.

I'm going to ask General Finishes themselves before I break out the Rotex.
If you put gloss over satin, you are going to get gloss that looks cloudy. With the gloss as the last coat, that's what you see from pretty much any angle. From straight on, with no direct light, you will see the flattening paste.
Think of it like a piece of glass and a sheet of waxed paper. If the paper is on top, satin. If the glass is on top, shiney but cloudy.
Title: Re: What is up with these streaks in my finish?
Post by: mrFinpgh on March 14, 2021, 11:05 PM
Quote
If you put gloss over satin, you are going to get gloss that looks cloudy. With the gloss as the last coat, that's what you see from pretty much any angle. From straight on, with no direct light, you will see the flattening paste.
Think of it like a piece of glass and a sheet of waxed paper. If the paper is on top, satin. If the glass is on top, shiney but cloudy.

That's what I would think - putting glass over something that isn't clear won't make that thing more clear.  I will do an experiment sometime to test the effect.

In the meantime, what I'm trying to figure out is what my next steps ought to be with the current iteration of this finish: all gloss build, with the intent to rub out the finish to a satin sheen.  I don't usually play with gloss (I don't usually use Arm R Seal unless it's satin and on oak or mahogany either) so I'm trying to make sure I get my process right.