Abrasive of the day...

Toby Newell · Jun 5, 2024

*invoking the spirit of Shadbolts on the A406 with their veneer of the week*

Todays abrasive is Festool Granat P240. Granat is a sintered ceramic alumina, after P120 it's a greater percentage regular alumina so quite soft but still with a little bite.

These discs are great for intercoat sanding where you need to denib but don't want to burn (break through) the finish.

Here they are being used on Bona Traffic HD penultimate coat.

The sander is Festool ETSEC150/3 the finest sander out there. Remember to use a thick interface pad and turn your extractor down to low so the suction doesn't stop the pad rotating freely.

Lacan07 · Jun 5, 2024

I got some P240's, not used them yet though.

mardinor · Jun 6, 2024

What's your view on mesh abrasive, Toby? Or is the dust extraction good enough anyway on the Festool combo?

Have you tried 3M Cubitron? Haven't myself as I've got a batch of Abranet I'm still working my way through.

Toby Newell · Jun 6, 2024

mardinor said:
What's your view on mesh abrasive, Toby? Or is the dust extraction good enough anyway on the Festool combo?

Have you tried 3M Cubitron? Haven't myself as I've got a batch of Abranet I'm still working my way through.

I don't use mesh, no need, Festool extraction is better than Mirka et al with mesh. Also mesh has fatal floor, it eats backing pads, you need to use a thin interface pad, they call it a 'saver' but you only need it for mesh.

You are eating up my future posts

I have tried all UK available abrasives! 3M cubitron has many forms.

3M 775u and 737u, very sharp, great for sanding filler, paint and resinous timber although it blunts quite quickly and colleagues and I have found the backing can overheat and detach from the disc. Dust extraction isn't great either with the spiral pattern.

^^^ 3M cubitron 947a and 950u however, fantastic discs, super aggressive, 950u is a lightweight backing super open coat, super sharp, the P60 is amazing, it suddenly blunts, which is weird, but cuts very well.

947a I think is the same abrasive but extra closed coat, heavyweight backing and resin over resin bond and is more durable, amazing abrasives but 947a is silly expensive £2.50 per disc, if you can find special offer for less than £1.00 per disc then makes sense.

Toby Newell · Jun 6, 2024

Mesh discs only really make sense if you are sanding pure filler or plaster on verticals and edges, not really needed on horizontal or timber. Mesh is supposed to be gentler but it's not really, it depends on the abrasive. Mirka is, v expensive for what you get because of marketing. If I use net discs I prefer Sia (made in Switzerland) they do a 7900 net that is comparable to Abranet and 7500 ceramic net which is comparable to Abranet Ace, just much cheaper.

Along my long journey I have used Mirka, years ago but not these days, I think I still have a few boxes of Quicksilver P80s left, but they don't make the best abrasives IMHO and very poor VFM, I use mainly Festool, 3M, Sia and a few Norton ceramic. Mirka are simply heavily marketed and sold at Brewers etc. The top 3M and Sia abrasives are only really available online.

Toby Newell · Jun 6, 2024

Lacan07 said:
I got some P240's, not used them yet though.

240s or 320s for intercoat sanding, or stearated Silicon Carbide for hand sanding. All the floor lacquer manufacturers state you can use P150 on a screeder, but that's big fat Brazil nuts if you ask me, especially on stained work. You can flatten nibs and get a great key with P240 or P320, you just have to be quite thorough.

Toby Newell · Jun 6, 2024

Mesh discs fray, leave a lot of debris and are useless on rough or very old timber, they only really work in the P60 to P150 range, so great for painters sanding emulsion paint, filler and plaster.

Kudos to Mirka, they created the Ceros sander, then the Deros (Ceros without the transformer brick) which were basically small, ergonomic 240V copies of a pneumatic airfed sander. Festool copied them with the arguably (IMHO) better ETSEC150.

Then Mirka took the industrial 17in and 16in screeder mesh discs and cleverly shrunk them for use on the small 6in sanders. Because Mirkaspend a lot on marketing to the decorating trades this has managed to pursuade a few painters to join humanity in the new millenium in using sanders and dust extraction. Which is a good thing.

Sia do mesh and in general Sia is a higher class abrasive, possibly the best. Festool Granat look and behave suspiciously like Sia 1950. It's possible they also make the mesh discs for Festool too.

Sia discs are a bit cheaper than Festool but if you want the Festool hole pattern they are special order from Switzerland and don't work out much cheaper. I petitioned everyone to sell them in the UK, they would make a killing, but this all adds weight to Sia making abrasives for Festool.

Toby Newell · Jun 6, 2024

Bona abrasives are made by Sia.

3M and Sia are pretty much equal at the top, I think I've used 150 to 200 discs already in the last week on this job. I normally carry around £1500 to £2000 worth of discs on me.

Toby Newell · Jun 6, 2024

Good for hand sanding too (Festool Granat P240 on AC two pack cellulose.

Toby Newell · Jun 8, 2024

Todays abrasive is 3M 245 Hookit (3M's term for velcro) P40.

3M 245 is an excellent workhorse abrasive, it's 'only' aluminium oxide when many high performance abrasives are either ceramic or zirconia but it's one of the top performing aluminium oxide abrasives.

It only comes in P40 to P120 and I mainly use it in P40 and occasionally P60. It's great for stripping coatings and filler and leaves a gentler scratch pattern than ceramic or zirconia. I have used it in P80, P100 and P120 but it's better for coarse use IMHO.

It has a heavy E weight paper with a fantastic woven textile Hookit backing that NEVER peels off (looking at you 3M cubitrons...) and a resin overbond.

I use 3M 245 a lot, it is especially useful where a more durable disc is needed, like sanding very rough old timber with nails etc.

The only downsides are dust extraction and availability. 3M 245 mostly comes in no hole although 6,7,8 and 9 holes are available, so ok for some Bosch and Makita patterns, if you have a Festool, you are out of luck.

Still a great abrasive and it comes in all shapes and sizes, discs and sheets. It makes a marked step up in quality for example to the painters favourite, Oakey Liberty Green.

Because it has a softer grain than a ceramic or zirconia it is more forgiving for beginners.

I can even use it on my industrial edgers and geared multidisc screeder, a true classic that I have used since I first started and that I will continue to use.

Toby Newell · Jun 8, 2024

Incase anyone is wondering how I know so much about abrasives... this is less than 2 weeks worth on this one job, probably got another 50 or so to go...

Toby Newell · Jun 9, 2024

Todays abrasive is Sia Siaspeed 1950, P120.

When staining it's important to have an impeccable surface finish before you start, as a belt and braces approach I water wash to raise the grain then cut back with P120. Any finer and you close over the grain, any coarser and you might see sanding marks (pigtails) You want an abrasive with nice bite that lasts long but doesn't leave deep marks.

Sia 1950 is a lovely ceramic abrasive, super aggressive at P40 - P80 and nicely balanced from P100 (finer grits are high quality semi friable / blue fired aluminium oxide blend for a gentler scratch pattern) I use them in all grits.

Sia 1950 comes in every hole pattern, although Festool pattern is special order from Switzerland, it has a lightweight backing and good resin bond.

These are very similar to Festool Granat, colleages and I suspect Sia could even make Granat for Festool (Sia have made abrasives for Bona for decades) they basically look, cut and last very similarly.

Brilliant all round abrasive, the only real downside is the lightweight paper backing which sometimes makes them unsuitable for very coarse work. If you are coming from DIY shed abrasives like lower quality generic Bosch Redwood, Dewalt etc they will be a revelation.

Toby Newell · Jun 11, 2024

Todays abrasive is SAIT Saitac 6A lubricated P240... and FYI. Don't buy it!

I ordered by phone from Jenkins, possibly the most traditional wood finishing company in the UK. They are great, but everyone makes mistakes, I asked for 'lubrisil' (which isn't made anymore and stood for 'lubricated silicon carbide') and instead they sent me this...

Sait Saitac 6A is similar in that it has a lubricant additive, nominally aluminium stearate which is a metal soap but the abrasive is aluminium oxide and the paper weight is B. This makes it longer lasting but can leave rogue scratches. Excellent for intercoat sanding on floors for example but not the best for extra fine work like sanding French polish on high build finishes for example.

Nothing wrong with Sait, they are made in Italy and I would rate them as a second string top tier manufacturer, not the best but very price competitive with a very wide range. They make 80 and 90mm discs and delta sanding sheets for example down to very coarse grades (P24) I use them here and their P24 silicon carbide industrial edger discs.

However, I would skip this abrasive and just buy what I thought I was getting which would be 3M Frecut Tri-m-ite or Sia Siarrex Fine 1748. These are similar but have the lightest A weight paper and a sharper yet gentler (extremely friable) silicon carbide abrasive. They look the same! But the 3M and Sia papers are much more forgiving and really the only thing you can use on very fine work apart from worn high quality sanding sponges. These abrasives are essential on fine or gentle work, if you need to sand the shellac sealing coat for example on stained work. I use them on shellac when polishing antiques, fine furniture and for cutting back sealer coats before waxing or lacquering. Excellent abrasives.

They start at P120 - P150 and go up to P400.

In general I use P240 for heavy cutting back of sealer on bare wood or P320 on stained work. For extra fine work, eg when French polishing I use worn P400. On some of the joke 'French polishing masterclass' youtube videos I see people intercoat sanding with things like new P180 sponges. Needless to say following the joke videos will ruin any article you are working on!

Toby Newell · Jun 11, 2024

^^^^^ Top tip. If you rip paper in half (crease and rip across table edge) and fold in quarters then two of the four sides rub against each other and dull, so...

Take each half sheet and then fold it into thirds instead, like an A4 letter. You now need to carefully flatten out three fingers (and possibly pop your thumb behind to hold the paper together) to stop the paper from rucking (you can put pressure on half of the third face then swap round) but voilà no abrasive on abrasive dulling action.

For example, if you wanted to do a very basic wax finish prepare the bare wood to at least P120, apply one or two coats of shellac sanding sealer eg Mylands 2000 sealer, let dry fully (the longer the better) then very thouroughly cut back with P240 trimite or siarrex. If the resulting surface isn't one of the smoothest things you have ever touched something has gone badly wrong. It's easy now to clear coat or stain coat with a wax using a brush and soft cloths. This gives a very high class, low build finish that is almost beyond smooth. Great for door sets.

a twig · Jun 11, 2024

When I’m looking at the hardboard doors that need replacing here this doesn’t help!

Toby Newell · Jun 11, 2024

a twig said:
When I’m looking at the hardboard doors that need replacing here this doesn’t help!

lol those are pretty cheap doors tbh. Paper thin veneers and routed quirks straight to the mdf. Bugger to get smooth if you don't know what you are doing. You have to sand each face of the quirk.