Rubin sandpaper, my relationship with it.

Brice Burrell

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Mar 13, 2007
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It's time to starting talking Festool again guys, here we go. Festool's Rubin sandpaper, if you have ever used it, like me, you might have a love/hate relationship with this sandpaper. 

This paper is made for bare wood, it's on a mid-weight paper and stands up against tearing fairly well. The grit particles on Rubin are both base and top bonded (adhered to the paper). The top bonding is closed-leveled, this means only the tops of the grit particles, in this case aluminum oxide, are exposed and the valleys are filled with the bonding resin. This bonds the particles to the paper really well, helping extend the paper's service life. It also has a top coat specifically to, as Festool says, shed wood fibers. What that coating is, I have no idea and I'll take their word that it works.

So, how does all of the information above play out in real world use? Well, this is my take, I love this stuff, when I slap on a new sheet of Rubin paper it cuts like a dream. That new sheet cutting action doesn't last all that long, this is where the hate part of the relationship comes in.

Rubin paper is like the radioactive material Tritium, it has non-exponential decay. Tritium reaches its "half-life" relatively quickly and then the decay slows considerably, Rubin is much the same way. The sharpness of its particles dull to about half of their life very fast compared to how long the pager last before it stops cutting all together.

When you first start to notice this slow down in cutting take a look at the paper, it still looks new. It sure is hard to throw away a new looking piece of sandpaper, so don't do it, I'll tell you why in a minute. First here's my theory on why I think the cutting seems to slow down so fast, I think it's the closed-leveled top bonding. I suspect the tops of the particles are wearing down and the "filled valleys" are left to do the cutting. Sanding with these filled valleys is like using a higher grit (more grit particles). You'll spend a lot more time trying to sand with paper that is dull or you'll sped more money using more sheets changing them out for new ones all of the time. What's a guy to do?

I charge my clients for the sandpaper I use, so this issue isn't much of a problem for me. However, if you are paying for your paper consider this approach. Keep the old sheets and use an 80 piece when you really want a 100 or 120 grit. This is be no means a perfect solution, it is the best thing that I've come up with for extending the usefullness of Rubin paper.

Keep this mind when thinking about buying Rubin, get a grit or two lower (fewer grit particles) than you think you'll want. These are some of my thought on Rubin paper, I would love to hear what you think.

 
What are the Rubin particles Brice?

Some particles get blunt but retain most of their form, however they change from cutting to burnishing.
Check by looking for a sheen in the sanded area.

Friable particles like aluminum oxide will literally break down into smaller particles effectively becoming finer. You can start on a (modest sized) rough board with 80 grit and smooth down both the wood and the abrasive till you're ready for a seal coat, if time isn't worth much.

Work gets done faster if you change grits, but it's tempting to wring all you can out of a disk. Especially if you're a cheapskate like me.
 
Hi,

  My thoughts  are - you do indeed get that initial fast cutting for maybe a couple minutes. Then it levels off, but is still cutting very well , and for a long time after that. I think it is part of the plan for that paper.  I also notice that when it is worn it really drops of cutting quickly. I have learned to notice this by paying attention when sanding.
    That idea of the grit getting finer is interesting and may very well be occurring. That would somewhat explain that long plateau before it really dies.
    I use Rubin 100 and 150 on the ETS150. Then I move to Brilliant 180. I do still find that the Brilliant 180 cuts finer than the  Rubin 150.

 

Seth

 
Well, you may be doing this already, but a rubber stick really makes the paper last longer. I do re-rate paper finer, but rubin is best for the 24-120 range for me. (so I don't re-rate it up to the point that I've started worrying about the finish)
 
Joel, that is one alternative, and it one that I'll be looking into more closely when I have the time to really dig into the costs/pros and cons involved in using Crystal over Rubin for everyday use.

Underused, I remember your comments, I believe they were in your review of a Festool sander. If you don't mind would please repost your thoughts here so we can discuss them here also.
 
I find Cristal to cut longer than Rubin. Either way, I do the same thing and stop when a sheet no longer seems effective with the hope of using it later on where I might not need to be as aggressive. When I was a teenager I worked for a mechanic that seemed to keep every spark plug he ever changed out. They were packed away for an eventual use, I guess. I think I am becoming that guy. ::)
 
I hear you. I'm pretty rational about whether I'll use a really doggy piece again, but I still have a stack of used disks.

BTW, on a slightly related topic, I successfully cleaned tung oil off a sheep skin today by saturating it with the oil (Organoil ) and running it over a stretched piece of terry cloth until it was clean. Got all the gunk off. Sheepy's all fluffy again.
 
joel moskowitz said:
Almost all my Rubin customers are now switching to Crystal. Lasts long, cuts better, etc.

I don't have many complaints about the Rubin paper really. I've gone through a small boat load of it (50-60 boxes of it at least) and think its a step up from Norton and other comparable papers. However, I agree 100% with the above comment on Cristal. It costs more, but I find that it last so much longer and works so much better that it pays for itself rather easily. I've been doing a bunch of work with preprimed pine lately (ugh... I really HATE that stuff). With the Rubin, in grits 100 and higher, the paper fills up very quickly (I know that's the wrong use for the stuff, but I can't keep a large selection of brilliant with me on jobsites). The 50 and 80 grits in Rubin work MUCH better though. The Cristal, in all the grits I've used, doesn't clog up much at all and it cuts dramatically faster for this use. By using a rubber stick every so often, I can prolong the life of a piece of 80 grit cristal for about half an hour if I really want to. With the Rubin, its pretty much dead after 5 minutes (I'm not the type to try and stretch the life of sandpaper normally, efficiency is more important to me than the cost of the paper).

Having said the above, I've been very happy with the Rubin on bare hardwoods though. Really no complaints at all. Afterall, that's what that paper was intended to be used for. I pretty much agree that it starts out really sharp and fades quickly. However, I think that once the initial sharpness is gone, its still cutting just as well as other papers do when they are fresh.

Brice, if you're like me, you probably don't always have the correct paper on hand. That's what so good about the Cristal. It works very well for just about everything. 
 
Back is great, thats why I haven't been around here much. I'm actually able to work 15 hours a day again  ;D

Thanks for asking.
 
Has anybody tried lowering the speed of the sander to see if it makes a difference on the Rubin? WHat about downward pressure?

I am wondering if heat build up has something to do with the quick wear on the Rubin paper.

Dan Clermont
 
Does anyone know what the abrasive particles are in Rubin? From the descriptions of it's behavior it sounds like a closed coat aluminum oxide. Al oxide will break down from sharp mountain peaks into fresh sharp shorter hills but that breakdown is limited by the coating in the valleys. Without the empty space in the valleys the shortened abrasive particles can't reach into the wood so progress is much slower.

With valleys full of the coating there is also less air flow so the disk will also get hotter in use.
 
Dan Clermont said:
Has anybody tried lowering the speed of the sander to see if it makes a difference on the Rubin? WHat about downward pressure?

I am wondering if heat build up has something to do with the quick wear on the Rubin paper.

Dan Clermont

Since Rubin has a higher density of abrasive particles particles it would follow that it would generate more heat than Cristal. Also, it would float on the surface more readily with the same amount of pressure, think sleeping on a bed of nails, meaning there might be a tendency to apply more pressure to get it to bite. This means even more heat. Lastly, there is less room between particles for cooling air flow. All these add up to Cristal being more free cutting. The downside seems to be that it leaves a slightly deeper scratch pattern than the same grit Rubin. Ah! That's what we can do with those dull Rubins. We can follow the Cristal to get rid of the deeper scratches.  ;D

Michael just pointed some of this out, I see. Rubin is AlO2 grit.
 
I think it has to do with the grain. Ao tends to dull as it heats up. That will give you that 80 starting to finish like 180 grit.
 
With the mean age on this forum being pretty high and the thread being from 6 years ago theres a chance the people your responding to are deceased. Just sayin!
 
rizzoa13 said:
With the mean age on this forum being pretty high and the thread being from 6 years ago theres a chance the people your responding to are deceased. Just sayin!

Good point, however checking profiles of respective posters on this thread yields only one as last active on FOG in Sept 2008, so in this case it is not truly relative - however the time frame is quite long for a response to the thread. Also just sayin!
 
Dreid said:
I think it has to do with the grain. Ao tends to dull as it heats up. That will give you that 80 starting to finish like 180 grit.

[welcome]

I'm almost exclusively using Granat these days [wink]

Kev.
 
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