Arm-R-Seal help

[Steve Gerger]

Hello,

Can anyone shed some light on Arm-R-Seal. I am finishing a corner shelf that is made out of solid cherry. After sanding the entire shelf with 180 grit I used Seal-A-Cell oil base first, and let that dry for two days. Then I lightly sanded with 320 grit sand paper and after cleaning it off with a vacuum I started to apply the first coat of Arm-R-Seal oil base. Letting that dry for 24 hours, I sanded it again with 320 grit sand paper and applied a second and third coat each time sanding and cleaning it. After the third coat was dry, I looked at it and at the right angle I can see lots and lots of very fine scratches that appear to be from my in between coat sanding. I would like to see if I can hide these scratches by adding another coat of Arm-R-Seal, but I don't want to add anymore scratches to it. Is it ok to add another coat without sanding or like some finishes is it mandatory to give it a scuff so the next layer has something to bond to. I'm new to finishing so any help would be greatly appreciated. Thank you in advance.

Steve

[Jim Becker]

You do not need to do continual "thorough" sanding between coats...knock off any dust, etc., with 320/400 "if necessary" and put on more coats. When you do sand, be sure you're constantly cleaning so that any abrasive debris are not causing extra scratches, too, and only very lightly sand if it's for adhesion.

[Phil Mueller]

As Jim said, very light sanding just to knock down any dust nibs. I usually use 600 or 800 between coats. It just doesn’t take that much between coats.

In your case, I think I would give it an even sanding with 600, remove the dust (I use DNA) and apply very light coats. Subsequent coats should even out any fine scratches.

[John TenEyck]

Are you sure the scratches are coming from your sanding between coats? I did a table top with Arm-R-Seal gloss and only noticed the scratches in the underlying wood after I had applied several coats. It took two more coats to convince myself the scratches really were in the underlying wood. The solution was a complete stripping and resanding which wasn't fun but had to be done.

John

[Phil Mueller]

John makes a good point (as usual). If you’re using gloss, every little imperfection in the wood will be magnified. I typically use semi-gloss, but even with that have had an occasion that needed sanding back down to the wood.

[Todd Mason-Darnell]

I most going to make the same comment as John about possible scratches in the underlying wood.

While no expert, I would not jump from 180 to 300 without a stop at 220 (and that is generally where I stop sanding the wood). Also, I am guessing you are using the Arm R Seal wiping formula...as others said, no need at all to really sand between coats...the film you are putting down is really, really thin. I generally go 3-5 coats before I even think about knocking back the nubbs.

[bill epstein]

Hello,

Can anyone shed some light on Arm-R-Seal. I am finishing a corner shelf that is made out of solid cherry. After sanding the entire shelf with 180 grit I used Seal-A-Cell oil base first, and let that dry for two days. Then I lightly sanded with 320 grit sand paper

Steve

Just to summarize, you sanded the finish with the right grit, but not the raw wood. As far as the raw wood goes, whether you sanded right from the planer or after hand planing and scraping makes all the difference.

You don't mention planing so especially for a gloss finish to go from machine to finish I would start with 100, then 150, then 220 garnet by hand. For Gloss Plastic-thane 320 or even up to 400 is indicated.

As others have said, you really have no choice but to remove the finish and begin again.

[Mike Monroe]

Unless the scratches are really noticeable, I wouldn't worry about them. Too often I obsess about minor imperfections on a project that no one else notices. When I framed houses for living we had a saying - "You're not gunna see that galloping by on a horse at night.".

[Jim Becker]

Mike, many of us have internal constitutions that require us to make the best effort even if nobody else would ever notice like you mention. Even when working with house framing!

[Dave Zellers]

The cherry will darken considerably within a year and no one will ever see those scratches made by 320 sandpaper.

[Bennett Ostroff]

Mike, many of us have internal constitutions that require us to make the best effort even if nobody else would ever notice like you mention. Even when working with house framing!

Amen, Jim. And even if I don’t always fix a small defect, I like to know why it happened so I can avoid it in the future.

Re: the scratches, I’m always shocked at how low a grit manufacturers recommend sanding in between coats for oil based poly/varnish. 220 is way too rough and will scratch the hell out of it if sanded under 24 hours. I usually use 400 or 600 grit. On the other hand, I sand water based poly fairly aggressively with 220 or 320 after two hours and the scratches never show under the subsequent coat.

[Jim Becker]

Bennett, I suspect a lot of those manufacturers are "talking" to the home improvement/contractor crowd, rather than fine woodworkers, when they suggest 220 grit between coats. You'll be hard pressed to even find much abrasive finer than that in home centers and lumber yards. Woodworkers making furniture, etc., learn very quickly that's not the best because we look at our project more up close and personal.

[Phil Mueller]

So true. It didn’t take too many times before I realized the recommended grit was not the way to go. I start with very fine (at least 600, if not 800 or 1000). If it corns Or clogs quickly and/or doesn’t do the job, I can always drop down to something coarser.

[Frank Drackman]

I got my start spraying in auto body shops where we went sanded a lot. I still use it when sanding between coats. I put a light mist with a spray bottle & usually start with 1000 grit.

[Dave Zellers]

Another thing that could be happening is a loose grit particle from a lower grit sandpaper could fall off the sander and get trapped between the sander and the wood. Good practice would probably include turning on the sander away from the project before applying it to the surface to allow the vibration to shake off any loose particles.

Anal practice (my speciality ) might include blowing off the sander with compressed air between grits. But even I don't do that.