The Sanding FAQ – EVERY Myth Dispelled!

Feb 12, 2014 | How To, Sanding

The Sanding FAQ
(frequently asked questions and some others I threw in for the heck of it)

Why do some disks fall apart? Backing separates from the paper.

When hook and loop (H&L) sandpaper is made, the sandpaper material is bonded to a fabric type back. The way that the fabric is bonded makes a big difference for woodturning applications. Woodturners use smaller disk at a higher speed. This speed generates more heat than a typical woodworking application. This heat will often melt the glue bond and the sandpaper will separate from the fabric. Another problem is some the glues are too brittle and the backing just comes right off because of age.

I hear about different “grading” for sandpaper, why am I confused?

It is pretty easy to get confused. Essentially, sandpaper is graded so you know which is the most coarse grit and next, etc. The most common methods are CAMI used by US manufacturers and what is commonly referred to as the P grit system (FEPA), common in Europe. They are pretty much the same to around 220, but it goes wacky from there. To further confuse things, micron graded paper is another system and Micro-Mesh has 4 different systems. A handy chart can be downloaded here.

Why should I buy so many different grits? Why can’t I just use every other one?

I hear this question a lot. While it would appear on the surface that if you skip grits, you only use half the sandpaper and that would save money. The reality is when you start with a grit, it cuts the surface based on that size. Say 80 grit. You start sanding, making 80 grit “grooves” at about 150 microns, if you were to skip to 180 grit, you are trying to abrade away the 150 micron with 80 micron grit. With 120 grit, it would be much easier because you would be using 125 micron grit. While you could skip SOME at the lower grits, usually from 80, skip 100, use 120, skip 150, use 180. My usual routine would be 80,120,180,240,320,400. If I am going above 400, I would not suggest skipping at all.

What size disks or pad should I use?

If you can only afford one, definitely go with the 2″. I would say that most of my bowl, hollow form and faceplate work under 10″ is done with a 2″ pad. The pads are less expensive and so are the disks. 3″ is great for the outsides of bowls and convex shapes and the inside of larger bowls or more gradual curves. Too tight of a curve and the 3″ pad will only hit the edges of the disk and not the center. For large work and especially large platters, 3″ is good. Now the 1″ is a bit different, in that it is intended to be used with the lathe off. The main reason is there is so little surface area for the hook and loop to grab onto and the disk can spin off. They are great for cleaning up carving and other adornment detail.

At what speed should I sand ?

Most of the time, I would say to power sand at the speed you are turning, but generally, I slow it down so that any undulations in the grain the pad will follow and not skip off the surface at the high point. Another important factor to consider is that the faster the sanding pad and the work are going, the more heat that is generated. Heat, as you may have thought of, is your enemy. Heat will increase warpage, potentially induce cracking, and can also melt the little hook and loop fingers on the pad.
Essentially, slower is better. On micro mesh you have to be extra careful, as higher temperatures can actually soften the surface and start to melt the sanding disk.

What type of disks do you carry?

In short, we carry products made from Mirka Royal and Royal plus in 1″, 2″ and 3″ sizes. Mirka Abralon in 2″ and 3″ sizes and Mirka Abranet in 2″ and 3″. More info about each product and their uses can be found here.

What type of disk holders do you carry?

I did plenty or research and searching for the absolute best hook and loop holders I could find and tried a lot of products. I finally settled on the Tim Skilton pads made by Tim himself in Australia. These are definitely more pricey than those we typically see out of Taiwan, but I think you would agree that they are worth it. They are made with a hex shaft that is secured to a firm upper layer of foam with a nut, washer and tee nut. After that, a softer layer of foam is glued to the firm pad and the hook and loop (Velcro) is applied. More work, but durable and a good combination of foam, not too hard and not to soft. It is goldilocks “just right”. They the hook and loop can be replaced. For instructions, email me. They are available in 1″, 2″ and 3″ sizes. If you are in a financial pinch, we do offer an economy pad that works just fine with all of the product EXCEPT Abranet. The reason is Abranet is a screen and the economy pads use a micro hook that just doesn’t have enough surface area to grip Abranet.

How come you don’t sell “wavy” disks?

A few reasons. First, the wavy disk design is a trademark design and belongs to one person, second the dies would be cost prohibitive, third (and most controversial) is that I don’t think they are necessary. If you have a good quality material that is bonded onto a good flexible backing, your disk are going to conform to the wood deisgn better and will not dig in. The dig in is the whole theory behind the wave design.

Why don’t other people sell Mirka disks for woodturning applications?

Another long answer. But the short of it is that I acquired samples of many commercial sanding material manufacturers and did a lot of sanding. I felt that Mirka’s product was the best value. I am now a Mirka distributor and cut our own disks out of Mirka material. Mirka does not make disks in all the sizes we need for woodturning, so we make them for you.

Each of the disk you sell is really marked with the grit number on the back?

Yep! well, most of them. The 1″ are too small .
The truth is, that is a completely manual process. Before bagging, each disk is hand stamped with the grit number on the back. This way you can easily see through your dirty face shield what grit you have just picked up, or more typically, picked up off the floor. We had to do a bit of research to find the right ink compound for that. Most inks bled or took too long to dry.

How did you get into selling sanding disks?

I am an obsessed woodturner just like you. Around 1996 I called a vendor one day to order disks and found that most of the ones I wanted were not in stock, and they wouldn’t backorder what they didn’t have in stock, it was too small of an order. Upset and in an “I’ll show them” frame of mind, I started to think about how i could make my own. I now have a whole lot of commercial dies and a few presses. Heck, I need to use it too, so I might as well have a good supply on hand when I need it.

Really, the grit number is stamped on the back of all the disks?

Not all of them, the 30mm disks are too small. BUT, all of the 2″ and 3″ disks have the grit number hand stamped on the back. While this is a laborious process, once you drop a disk into the shavings, it is a pretty nice feature.

You claim the disk are easy cleaning and won’t separate, how’s that?

The disk we sell are stearate coated so the wood doesn’t build up as much and this layer will allow it to be easier cleaned. Sand a little, run the disk over a gum pad (like used to clean sanding belts) and sand some more. Repeat as necessary. If you are using real oily wood or some wet woods, they will build up a film faster and need to be cleaned more often.
As far as the backing not coming off, the Mirka products use a higher temperature adhesive to adhear the polyester backing to the disks.  Under certain temperature and humidity extremes, the glue could dry out and the backing come off (or if you are pressing too hard and heating it up too much). Should this ever happen, send it back and we will gladly replace the product, regardless of age.

Is woodturning an art or a craft?

How much did the piece you make sell for? Would you call $1000 hunk of wood on the wall craft?

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