Thread: Took a few sanding abrasives for a test run

Starting with the next available grit above #80, each grit was worked through until I got the best finish I could at #400. Very subjective, I know, but from experience I expect that my standard would satisfy most turners. Each piece was inspected under 40x magnification and with a bright LED light after the last two grits to check for any residual scratches not readily visible to the naked eye.

A new set of disks was used for each surface, except for the Dry Ice where I only had one set of each grit. These were gratis so I could include them in the test run, thanks Ern.

The lathe ran at about 1500rpm and the disks at 3000rpm for the lower grits and the lathe progressively slower for the higher grits (down to 250rpm). A very light touch was used.

A separate duration test was conducted and reported in a later post.


Abrasive: Vince's Ceramic Grip to #220

Wood: Oak, Diameter: 9" bowl, Surface: outside, Time: 35 mins + #320 buff for 8 mins, total 43 mins
Wood: Oak, Diameter: 9" bowl, Surface: inside, Time: 30 mins + Vince's Blue to #400to for 20 mins, total 50 mins
Silky Oak, Diameter: 7.5" bowl, Surface: outside, Time: 25 mins + Vince's Blue to #400 for 7 mins, total 32 mins


This ceramic was very aggressive, removing a lot of wood very rapidly but leaving a rougher surface than the grit rating would indicate which then required an effort to remove with the follow up abrasives above #220, and as a result the overall time to completion wasn't that good.

The sample Ceramic Grip kit included #320, #800, and #1200 Scuff Brite pads to complete a piece after the Ceramic #220. I didn't find these pads very abrasive or sufficient to complete a piece on their own. Closer intervals between the grit sizes may have worked better. These pads may have also allowed for renegade lower grits to be re-introduce and to re-scratch the finish, but I didn't have time to confirm this with further testing.

I also found that the white #1200 will burn if allowed to dwell on stationary wood...

The Ceramic Grip and Blue Flex 2-3/8" disks and the Cera~Max 2-1/2" disks all provide more abrasive than standard 2" disks (roughly 50% more) which is nice to have, especially on the outside of bowls, but I found them to be too large for the inside of small and medium bowls. They also require an interface pad to run on the standard 2" mandrels. There are some claimed advantages to using these adaptors, including saving the hook surface of the more expensive mandrel and selecting different densities of backing for different applications, but these may not be advantages that are seen as important to every turner.


Abrasive: No-Name Alox

Wood: Blackwood, Diameter: 7" bowl, Surface: outside, Time: 40 mins
Wood: Blackwood, Diameter: 7" bowl, Surface: inside, Time: 43 mins

The coating on the grit quickly wore off the No-Name abrasive but there was no clogging evident. The rate of wood removal began to slow towards the end of each grit. Going by the nominated grit size, the grit intervals were not predictable. With some effort the end result was satisfactory but slow.


Abrasive: Astra Dot + Kingspor

Wood: Mango, Diameter: 10.5" deep bowl, Surface: Outside, Time: 30 mins


I only had 3" disks for these abrasives so only used these on the outside of the test bowl.

The surface left by the #120 Astra Dot (the finest I had above #80) was the roughest of any left by the #120 abrasives. I then proceeded on to the #120 Kingspor which was needed to clean up the rough surface left by #120 Astra Dot. I was, however, reminded how grippy the Kingspor is. Too grippy for me to consider as an option with my fast and light technique. The time to get to an acceptable finish was better than the two previous tests, but not so pleasant getting there IMO.

Running up through the Astra Double after the Single Dots and then onto the finer Champaign may have been a difference experience, but I didn't have those to hand so can't comment on that option.


Abrasive: Dry Ice

Wood: Blackwood, Diameter: 12" platter, Surface: outside, Time: 35 mins
Wood: Blackwood, Diameter: 12" platter, Surface: inside, Time: 30 mins

Quick and aggressive, but loaded up chronically. However, surprisingly it had the best #400 that I tested, doing a good job of removing the #320 grit abrasions and also leaving minimal visible marks itself. The time taken to clean out the clogged abrasive was included in the overall times, which left it under performing despite its rapid rate of the abrasive cut.

The Dry Ice comes as a standard 2" disk, so didn't need any adaptors and would also work quite well inside smaller diameter bowls.


Abrasive: Vince's Blue Flex

Wood: Mango, Diameter: 10.5" deep bowl, Surface: inside, Time: 30mins
Wood: Blackwood, Diameter: 9" bowl, Surface: inside, Time: 35mins
Wood: Oak, Diameter: 8.5" bowl, Surface: outside, Time: 24 mins

The Blue Flex had a firm bite with minimal or no clogging. They did not feel as if they were nearing exhaustion towards the end of each grit and I expect they would kick on for a bit more than just one surface of a bowl of this size. The duration test will give a reading on this. It required my best efforts to get a satisfactory finish at #400 to avoid some fine residual abrasions, the sort that are just discernible with the naked eye under strong angular light. In defence of Blue Flex, they also supply a #280 between the #220 and #320 which I chose to skip when I was buying. The addition of this extra grit may have given a better outcome at #400.


Abrasive: Vince's Cera~Max

Wood: Cherry pine, Diameter: 8.5" bowl, Surface: outside, Time: 23 mins
Wood: Cherry pine, Diameter: 10"diam deep bowl, Surface: outside, Time: 20 mins
Wood: Cherry pine, Diameter: 10" diam dee bowl, Surface: inside, Time: 20 mins

This abrasive is a blend of ceramic and traditional alox. The claimed benefit is the best of "ceramic for long lasting wear and aluminum oxide for even grit consistency".

The Cera~Max worked quickly and smoothly, with minimal or no loading, but again I found that I had to concentrate to eliminate all residual abrasions at #400. There is a #360 disk that wasn't included with the sample pack and expect that this could make a noticeable difference to the quality of the final finish, albeit at some cost to the time required to finish the job. Given the speed of this abrasive, the addition of another grit to more readily get a better finish would add just a little extra time (3 to 4 minutes) and still leave it as the fastest abrasive I tested.

Cera~Max disks are 2.5" diam. My sample pack didn't come with the 2.5" interface pad so they overhung the supplied 2-3/8" adaptors. Had I been able to use the matching 2.5" interface pad I may have got even better results on the speed and endurance tests.


Next post: Durability

Watching.

The purpose of this test was to see how long each abrasive make would effectively work or how long before the backing failed. What might still be 'effective' for one person may have long gone past that point for someone else. For this test (but not necessarily how I work) the criteria was to use the abrasive until I could no longer feel a positive bite or until the stream of sanding dust coming off the wood dropped to about 1/3 of the initial volume. The two things usually happened about the same time. The volume of dust coming off the wood was observed at the mouth of the dust extractor hose intake which was positioned next to the work piece. A light coloured wood (Cypress) was selected so the dust from this could be clearly seen against the dark interior of the extractor intake. The outside of the same shallow 20" bowl was used to test all abrasives.

The #80 abrasives were initially selected for this endurance test, but after nearly 45mins on the first disk and about 10mm off the outside of the 20" bowl I gave that idea away. It was becoming an endurance test on me too. So I selected #180 instead, a better idea as this is about the mid-point in the normal sanding range and where the majority of the ground work is done for a good finish. And, all of the #180 abrasives should be predictably rated at about 80 microns, irrespective of the rating system.

Here are the times for the #180s.

Dry Ice #180: 18 mins
Ceramic #180: 18 mins
Kingspor #180: 10 mins
Blue Flex #180: 9 mins
Cera~Max #180: 9 mins
No-Name #180: 8 mins

As I did not have any Astra Dot #180 I ran a separate test with a fresh Astra #120 and compared this to Vince's #120 Ceramic and Cera~Max. All three abrasives were cut to 2"diam so I could run it on my standard 2" mandrel to avoid the interface pad cooking problem experienced during the #180 endurance test run, reported below.

Here are the times for the #120s.

Cera~Max #120: 70 mins
Astra Dot #120: 38 mins
Ceramic #120: 31 mins

In the case of the Cera~Max I gave up before it did. It was willing to keep going, I wasn't! It had made its point and I was ready to go home... )

A longer run time was expected at the lower grit, but what was not expected was the significant switch in performance between the #180 and #120 Cera~Max and Ceramic. For want of an explanation, the composition of Cera~Max is predominantly ceramic in the lower grits but progressively switches over to alox in the higher grits. So at #180 the Cera~Max was behaving more like an alox abrasive than a ceramic.

Not obvious from the raw times was the difference in how much wood each of these #120s was removing. The Ceramic and Cera~Max began by removing at least twice as much wood as the Astra. Not surprising given the difference in the amount of grit on each. At about the 13min mark the Ceramic was down to removing about the same as the Astra did initially. And, the Cera~Max kept removing wood at a rate exceeding that of the Astra for the full duration of the test. So the Astra removes wood more slowly but persists for longer than the Ceramic, by a bit, but it didn't start to compete with the Cera~max on rate of removal or duration.

There had been no observed difference in the rate of wood removal during any of the #180 endurance tests.

Another observation was that the Astra Single Dot threw the dust the least distance from the disk of any of the abrasives. This in part came from the dust not clinging to the wood and being slung away. The dot pattern would be the reason for this. As a result the dust extractor inlet was able to capture most of the dust before it escaped. This feature may be important to some.

Two other things to report. In the aborted #80 test run the backing on the Dry Ice disk failed at the 40 min mark. It was the only disk backing to fail during any of the tests. I also had two of the required interface pads cook during the duration test. The velcro layer started to separate from and move on the foam interface layer resulting in buckling and risk of total failure. Admittedly the #180 endurance runs were a harsh test exceeding normal practice, but worth noting anyway for anyone who might push these limits. @$4 a pop it's a consideration.


Attachment 162950 Attachment 162951


I had intended to repeat the durability test run on a decent piece of hardwood, but at this point my enthusiasm flagged. The results could be different if I had. Perhaps another time.

Next Post: Emma Chisset and some personal conclusions

On speed alone, the Cera~Max is very attractive, while its durability excels at the lower grits it sits acceptably along side the other lower priced options at #180. I also quite liked the feel of the Cera~Max on the wood and the finish. The durability of the required interface pads is still a question, as is the size. Those 2.5" disks will need to be cut down to go inside smaller and medium sized bowls. The economics of doing that is another consideration.

The pure ceramic options (Vince's Ceramic and Norton's Dry Ice) sure rip off the wood quickly but leave a surface that requires extra time to tame with non-ceramic abrasives. My results indicated that the overall time to completion wasn't significantly improved by using them. Their extra cost was commensurate with their durability but there is a question over the durability of the Blue Ice backing. Its propensity to clog was also a negative for me.

If speed is not such a factor for someone then Astra Dot is worthy of consideration, especially if you cut the disks yourself from rolls. Using a full set of Atra Single and Double Dot disks may also give a different result. It's non-clogging performance in wet and oily woods is a feature that may be an additional attraction for some turners.

I'm giving Kingspor a miss myself because of its grippy-ness but others may not mind or may even like this.

The abrasive I'm still not decided on is the Blue Flex. I think I need to get the missing #280 that I left out of my order to see if that makes any difference on the overall time to get to a good level of finish. I'm also going to have to give the interface pads more of a trial under normal working conditions.

So, for me, the price/performance sweet spot is looking like Cera-Max, and possibly Blue Flex, with a few questions still to be answered.

Whatever I decide, I don't think I will be staying with my current No-Name abrasives. Yes, cheap but not very efficient.

Your mileage may be different, but hope this has been of some use to you.

And, finally, some words from an acknowledged sanding expert, Bill Neddow,

"just remember, the sandpaper business is very competitive. You get what you pay for. Those extra cents you pay for the more expensive papers translate into longer lasting grit, better glues, backings and velcro and a more consistent grit pattern -– which cuts down the potential for those frustrating scratches that suddenly appear at times.

I know of only one shortcut that actually saves money – cutting your own disks."

See his article, "Sandpaper: New Grits, New Techniques, and Results of 10 Years of Testing", in Woodturners America, *here*

Thank you Neil. This is good information for those of us who would rather sand bowls than test sand paper.

thanks for an interesting, comprehensive post Neil. I have changed from cheaper papers to mid level stuff like astra dot in recent times and whilst I haven't measured anything, I do feel the longevity outweighs the cheapness. Also it's just plain less irritating to use nicer stuff

Cheers,
Dave

Excellent info.

[Thank you Neil. This is good information for those of us who would rather sand bowls than test sand paper.[/

you'll get an amen on that one!

I forgot a few things on the other abrasive thread, and this might be a good place to add them.

The interface pads. I love the contoured pads from Vince. Use the flat for the outside of the bowl, and the radius edge on the inside. I do stick with a firm pad for grits up to 220 or so, and then some times switch to the soft pads. 120 grit on a firm pad cuts better than 80 on a soft pad.

I have wondered how to do a measured comparative test on abrasives. You would need bowls from the same tree, the same size, and a jig to hold the drill in so pressure would be the same/constant. Also, some sort of a metered thing to make sure drill speed was constant.

If I can get a 3 inch disc inside a bowl, no matter how small the bowl is, I will use it because a 3 inch disc has more than double the surface area.

I have experimented with grit jumps. 80, 120, 180, 220, 320, 400. I have tried the jump from 180 to 260, and didn't like it. Mostly I figure that there will always be some scratches left from the 120, and the 260 just won't get them out while the 220 will.

From talking to Vince, with the ceramic abrasives, there are way less ceramic pieces in the higher grits because the manufacturers figured there wasn't enough benefit in durability vs cost to make it worth while.

I haven't tried out the 3M cubitron discs. Only available in grits to 220, and only available in PSA (sticky back), and not in hook and loop.

robo hippy

Thanks for sharing all this information. I am pleased that I came across it. While I am not into bowls as such I am more interested in learning how to carve large items and then how to finish them as near professionally as I can,

The tools I have are leaving me with a severe disadvantage but your articles, when I get my head around them, might open a few more doors for me.

Thanks for showing a sire with photo's of what you are talking about.

Pete

Originally Posted by robo hippy

If I can get a 3 inch disc inside a bowl, no matter how small the bowl is, I will use it because a 3 inch disc has more than double the surface area.

Hi Robo Hippy

I would suggest that using a 3" pad in a small bowl is not ideal for 2 reasons.

1: Only the outside of the abrasive disc gets any wear. Some turners then take this disc and punch a 2" one from the centre.

2: A smaller 2" pad better follows the contours of a small bowl.

A couple of observations.

A larger pad will not get as hot as there is a larger mass to absorb the heat being generated.

A larger pad will give you a smother surface on platter forms. It tends to take off the high spots and not remove wood on the softer parts.

I tend to use a 6" pad on large bowls and platters.

I hope this adds to the discussion.

Cheers

Tim

When sanding bowls, on the outside, I use mostly the center part of the disc. On the inside, because of the concave shape, I sand with the edge of the pad. When I am done with the disc, I might get a 1 inch disc out of the center, but most of the time the disc is totally worn out.

As far as the 2 inch disc fitting better than the 3 inch disc, that is true if the walls are steep, and the transition is sharp. On a more open form, all you have to do to get the edge of the disc into the transition is angle the disc a bit, rather than having it at 90 degrees to the bowl.

Not sure about the 3 inch disc running cooler. At the same rpm, the 3 inch disc will have a higher feet or meters per minute than a 2 inch disc.

robo hippy

FenceFurniture organised for some Jost abrasives to be sent to me for evaluation.

He has a separate thread running here on his evaluation of these abrasives for flat work. I'm concentrating here on their use for power sanding in woodturning.

I received from Jost some samples of their 2" Superpad P (P60, P100, P120, P180 and P400) and 2" Superfinishing SG and SG-2 abrasive pads (SG 600, SG-2 1800, SG-2 2500 and SG-2 3000).

The first thing I did was repeat the durability test (see post No 4) using the same test piece of wood (there was still some thickness left on it) using the same protocol as outlined above.

I began with the P120 pad to see how well it performed against the best performer last time, which was the Cera~Max #120. The Superpad P120 cut aggressively and continuously without any apparent loss of cutting power for 75 mins. As before with the Cera~Max, I gave up at this point. The disk was willing to keep going, I wasn't! It had made its point. It was at least as good as the Cera~Max.

I then did the durability test on the Superpad P180 to see how well it performed against the previously tested #180s. The value of doing this is that all #180 abrasives should be predictably rated at about 80 microns, irrespective of the rating system (US or Euro).

The Jost Superpad P180 lasted just 6.5mins when it abruptly stopped doing anything at all. Cleaning it with the rubber stick didn't make any difference at all. It was as dead as any abrasive I've ever attempted to use! The poorest performer of any of the #180 abrasives tested.

So, very mixed results on durability.

Because of the big drop in performance between #120 and #180 with both the Jost and Cera~Max abrasives I decided to run the durability test on the Kingspor #120 abrasive (I had already done it for the #180) to get more perspective on the expected difference in performance over that jump in grit sizes. The Kingspor went for 45 mins before dropping down to the designated half-output performance level. The output was only ever half as good as the Jost, from start to finish. Perhaps about the same as the Astra Dot. So not as good as Jost and Cera~Max but better endurance than the Astra Dot and Vince's Ceramic.

I should repeat the same durability test on hardwood, but not today!

Yet to do the test run for the Jost on 'time through to ready for finish'. I'll do that over the next few days.
.

75 minutes = an exhaustive test ;-}

Thanks for the post Neil.

Odd how different the results were for the 120 and 180.