Is this a job for Sanding Sealer?

[Zeddedhed]

I'm working on a project at the moment making an Oak Sideboard for a client. (I was going to do a WIP but it's not that interesting and is a direct copy of a piece sold online by M&S, only smallerised to fit the clients available space)

The project is going to be fitted in around several other ongoing bits of work and therefore the components are going to be handled a lot and moved around the workshop umpteen times.

I've decided to try and pre-finish as much as possible on this job as applying Osmo inside a cabinet isn't going to lead to the best results.

Having read a few books on finishing and browsed the forums I'm none the wiser as to what Sanding Sealer is actually for, but was told recently that one use is to protect components from dirt and grime after they've been sanded and prepped for finishing.

Is my source talking utter nonsense or is this a perfectly legitimate use for SS. If it is, then which type is best used with Osmo Polyx or Osmo Top?

 

[RobinBHM]

Sanding sealer does seal the grain, so it will stop finger marks -although it isnt really its purpose -mostly forms of finish will protect wood against finger marks.

I think the main purpose of sanding sealer is that it is designed to be easy to sand back, generally the solvent based types have zinc stearate added. Once the sanding sealer has been applied, it seals the timber and also stiffens all of of the wood fibres and particles of dust. Because it is designed to sand easily, the process of de-nibbing is easy as it cuts well with abrasive paper and doesnt clog.

My understanding is that the stearate in sanding sealer weakens the coat, so it is not ideal for filling grain of ring porous timbers.

Some water based lacquers are coat on coat and dont have a sanding sealer, but they arent so easy to rub back.

 

[marcros]

i would be careful of applying an oil inside a cabinet. air tends to get trapped there and it can smell a bit strong. for me, a sanding sealer is ideal for that, because it makes it much easier to keep clean, whereas bare timber seems to grab the dust.

 

[Random Orbital Bob]

And of the sanding sealers...Cellulose SS is the easiest to use from a speed point of view as it goes off really quick. Turners use it all the time because it allows whatever the topcoat will be (usually wax) to be applied literally a few minutes after the SS was applied. For that reason you also need to be careful as it's open time is extremely short. It can also be applied with a cloth so large areas can be done very quickly.

When 2nd fixing the house I now live in, we installed oak doors and agonised about what finish to use, not too glossy, not too flat. While we were trying to make a decision we decided to sanding seal them anyway as a prelude to whatever the topcoat would be and in that case we used a shellac based SS. It looked so good we left it without a topcoat, the perfect amount of sheen, it protects the wood and yet the grain popped out just as we wanted. It also has the advantage that if they get marked it can be sanded back and reapplied in patches that will blend perfectly in the future (within reason). That was 8 years ago and they're still looking great.

 

[Zeddedhed]

So, just to be sure I'm not being an utter dullard,
I should sand/scrape my workpieces first, then apply say Cellulose sanding sealer.
If I want to apply Oslo Polyx later I de-nib with something very fine (400g) and then Osmo as usual?

Is this correct?

 

[marcros]

i would seal, sand, osmo, denib, osmo

 

[Woodmonkey]

I wouldn't apply osmo over sanding sealer, it won't be able to soak into the wood as its supposed to. Osmo should be applied to bare timber

 

[Zeddedhed]

I wouldn't apply osmo over sanding sealer, it won't be able to soak into the wood as its supposed to. Osmo should be applied to bare timber

And therein lies the confusion.
I have a tin of Chestnut Sanding Sealer and it states on the tin that it's for use prior to application of, amongst other things, wax.

Wouldn't it inhibit the wax from entering the wood as well then?
Or does Wax behave differently from Oil in terms of soaking into the wood?
Osmo is HardWax Oil so does this behave like both Oil and Wax, more Oil than Wax or more Wax than Oil?

I may just start painting everything.....

 

[marcros]

if you don't stop wax from soaking in, you will have to keep reapplying it over and over, or it will dull quickly.

hardware oil- more of an oil than a wax.

 

[Phil Pascoe]

Someone made the observation quite a while ago - why would you chose to use for a finish something (sanding sealer) that is specifically designed to be scratched? :? Seems a fair comment to me. I tend to avoid it anyway, having spoiled a nice piece a long time ago with it.

 

[Flynnwood]

Ask OSMO - there is technical advice available from them. Worth a call - 01296 481 220

http://www.osmouk.com/retail/contacts.cfm

 

[Random Orbital Bob]

In turning you generally apply a wax finish over sanding sealer. The SS fills up most of the pores allowing the wax to not be wasted as Marcros has said. You can then buff the wax to a high sheen if that's the preference. Oil is generally applied direct to the bare wood, allowed to cure and then further coats added as desired. Once fully cured it can also be buffed to a high sheen. Quite where Osmo sits in that mix I'm not certain given it's described as both a wax and an oil??? I think the advice to call Osmo tek is good

 

[Zeddedhed]

The Osmo elves will be getting a call in the AM. I'll report back with any salient info.

 

[Zeddedhed]

Just got off the blower to Oslo tech support and here's what they told me: (this will probably cause a bit of a fuss)

If applying by brush or roller then only sand to 120g. No denying or sanding between coats.
2 coats is all you need.

If applying by cloth and wiping off, then sand up to (but no more than) 220g although 180g should be plenty in almost all circumstances.
Allow it to sit for a few minutes and wipe off excess.
No sanding between coats or de-nibbing.
Max of 4 coats.

Sanding sealer is apparently a waste of time if using Osmo (according to them)

Finish reaches full 'strength' after the final coat has had about a week to cure.

Food for thought.

 

[Phil Pascoe]

Why were you speaking to Norway?

 

[Zeddedhed]

Why were you speaking to Norway?

More to the point, how cool is it that the Norwegians have a tech support department for an entire city. Not only that but they know all about finishing Oil as well !! :lol: