Abrasives confusion

[guitar_ed]

Hi All,

I am confused, and I could use some help.

I am building a maple bookcase, and I finished it with Minwax ploy.  I let it sit overnight, and this morning I used my RO-125 with Brilliant-2 P400 to level sand, and it pretty much took the finish right off.  I tried both motion modes, and high and low speeds.  The results were the same.

What am I doing wrong?  If I am using the wrong abrasive, what should I be using?  And with what settings?

Thanks,

edg

 

[Tim Sproul]

Hand sand between finish coats.

 

[cgmojoco]

Hand sand between finish coats.

+1

Look at the Mirka vac blocks for hand sanding without getting harmful finish dust in your lungs.

 

[Ken Nagrod]

Not that you couldn't do it by machine, but hand sanding that poly affords you more control and any grit scratches will be inline with the grain and less noticeable as opposed to possible "pigtails".  Just give it a very quick, fine sanding for intercoat adhesion and dust nib leveling.

 

[semenza]

I often sand between coats of poly with a  random orbit power sander (ETS150/5). Usually with the Super Soft pad and very low suction.  With either 320 or 400 Brilliant 2.   Make several passes to get it thoroughly sanded rather than one slow pass. Also I generally apply two coats before trying to level sand with a power sander, much harder to go through the finish that way.

Sometimes overnight is not enough time for the surface to start getting really hard , often it helps to let it wait longer  before sanding.

Or as has been said hand sand with the grain, be careful  "turn the corner"  with the sanding block on the wood at the end  / edge of the piece you are sanding.

I have also just discovered that Granats no load characteristics are very good when hand sanding.

Seth

 

[AlexThePalex]

I also prefer to hand sand between coats.

 

[Scott B.]

I dont think its a sanding issue. Hand sanding in between coats is a profound time suck and dust generator.

This sounds more like its a product and application issue. Minwax is ok, not the greatest to work with. But one coat of it doesnt build much mil thickness, and while I am sure you didnt sand it all out at 400, I'd bet you got most of it.

There are a couple of things you can do. Go to a different, faster drying product so that you can do multiple coats in a day. I do this routinely with Zar Ultramax, at times even rolling (edit: not literally rolling, figurative) in a sanding sealer coat (which is super fast drying and really gives you something to build on fast) and then sanding with any of the ets, rts, dts options at even just 220 or 320 prior to a final coat (sprayed or brushed).

I'd ditch the minwax. Also, use Granat.

 

[Brice Burrell]

I have been using Minwax poly for over 20 years & it works great. My customers love the finish & it holds up very well.......

Myself and my brother have used Minwax oil poly for years too, but not anymore.  The last batch was abysmal.  The satin was practically gloss and there were adhesion issues.   

 

[Ken Nagrod]

I have been using Minwax poly for over 20 years & it works great. My customers love the finish & it holds up very well.......

Myself and my brother have used Minwax oil poly for years too, but not anymore.  The last batch was abysmal.  The satin was practically gloss and there were adhesion issues.   

Brice,

I'm a little confused.  Was that abysmal satin or abysmal gloss?  It's not on their website.

 

[BUTTER]

Yes, you have more control hand sanding, and it really doesn't take much time at all.

And try two coats of sanding sealer for your initial build.  Varathane makes a decent one for use under polys.  If you want to add some depth, use a shellac sealer (but make sure it's "dewaxed" shellac if you are usingw it under poly.)

 

[guitar_ed]

Hi Everybody,

Thanks for your replies. 

I did a bit more research, and here is what I learned:

1) I did not burn through the poly.  I thought I did, but it was just the poly VERY scuffed and looking really ugly.  And a bit dusty.
2) This morning I sanded down one panel with my RO-125 and Brilliant-2 P400, then I went over it with the MicroMesh series of hand wet sandpapers.  It's looking pretty good.
3) For reasons of time & mess, I would prefer to use Granat abrasives, but the only "local" place that has them in stock is Japan Wood Worker. (They are in Alameda, CA, which is a nightmare to get to.  The people are nice, and know what they are doing, but going there is not likely to happen.)

Thanks much, and have a good day.

edg

 

[RONWEN]

Hand sand between finish coats.

+1

Look at the Mirka vac blocks for hand sanding without getting harmful finish dust in your lungs.

+1  They are GREAT.

 

[guitar_ed]

So, more learning.

2 coats of Zinsser shellac based SealCoat, followed by a scuffing/levelling with the RO-125 and P400 Brilliant 2, then followed by 3 coats of MinWax Poly, then another scuffing/leveling with the RO-125, leaves the finish in great shape for final sanding and polishing.

BTW: Using a sanding block and elbow grease with P400 sandpaper did not leave as smooth a finish as the RO-125 did.

Take care,

edg