Sanding Oak Doors?

[^woody^]

Spoke to the door suppliers today, they advised not to use Osmo oil on my veneered doors as it can affect the glue

That's old fashioned advice, and it seems to be on every single veneered door you can buy.

I've used Omso door oil here at home and on jobs on various veneered doors from various suppliers and it has not affected the glue, and the finish is brilliant.

Doesn't that Johnston product and any similar 'non-oil' leave a visible surface coating that detracts from the actual wood finish? Like varnish?

Use scotchbrite pads or sheets instead of steel wool or sandpaper

 

[Deleted member 174758]

Use a bit of 250 grit paper followed by 400 and 800.

Removed

Oak is a very coarse grained, open pore timber, so there is rarely a need to go above P120 grit sandpaper as you don't gain anything from so doing. Were it already lacquer finished I might concur with the need for a fine grit, but it isn"t.

The main thing is for the OP to sand in the direction of the grain and, as you say, wipe off any dust with a home made tack cloth when finished. Pencil marks can also be removed using a clean dish cloth dampened in clean water (works on painted surfaces, too) although this can raise the grain and require a bit of sanding afterwards

The thing about steel wool is that it can leave tiny steel threads trapped in the open grain - any water, such as that found in a water based finish, will combine with the tannin and acetic acid found naturally in oak and attack the steel wool, creating an iron oxide which will generally be black. This is also whyvyou should only use brass, bronze or stsinless steel.fixings and fittings on oak or oak veneered products

 

[foxhole]

Veneered doors I saw last stated oiling the doors would invalidate the warranty .

 

[Deleted member 174758]

Veneered doors I saw last stated oiling the doors would invalidate the warranty .

The decorators I've worked with on several jobs used to use Sadolin on oak. Expensive, but a really nice finish and durable

 

[opps]

Veneered doors I saw last stated oiling the doors would invalidate the warranty .

Out of interest, did the manufacturer permit the use of water and, or, oil based paints?

 

[opps]

The thing about steel wool is that it can leave tiny steel threads trapped in the open grain - any water, such as that found in a water based finish, will combine with the tannin and acetic acid found naturally in oak and attack the steel wool, creating an iron oxide which will generally be black. This is also whyvyou should only use brass, bronze or stsinless steel.fixings and fittings on oak or oak veneered products

I don't understand why anyone would use wire wool on a door in the first place given that you can use webrax or some thing flexible like Abranet.

Wire wool is horrible to work with.

With regards to pencil marks, I use a very, very, very slightly damp cloth and dip it Red Devil One Time Filler- it works as a extremely fine abrasive. I picked up the technique back in the day when I specialised in painting raw MDF cabinets. Pencil erasers didn't cut the mustard. One day, I noticed that a cloth with the filler on it worked well. The cloth is so dry that grain swell is almost negligible.

 

[opps]

Why didn't they remove the marks themselves???
Use a bit of 250 grit paper followed by 400 and 800.
Don't forget to wipe the whole door with white spirit before treating.
In fact, if the pencil marks are not too heavy, they should come off with white spirit.

Back in the days when I used to spray MDF with 2K paints, technical support at Morrells told me to never go over 320G between coats. Their reasoning way that going for a higher grit would effectively "polish" the surface and impair the adhesion of further coats.

Granted that was 2 part paints, but I took it on board. A normal human should not be able to see score marks created by 320 grit paper if the surface is sanded with a decent DA sander using decent abrasives, and with the sander connected to a decent dust extractor.

Random orbital sanders are extremely effective, unfortunately , when used without efficient dust extraction, or appropriate abrasives, they will leave squirl marks.

I do still have some very high grade papers for my sanders, up to 2000, but I would only ever use them as a pre-polish before working up to 10,000 cutting compound. I have never used them, I don't need top end car spray quality, and frankly, I don't have the skill set or spray set up for that level of finish.

Apropos white spirit to remove pencil marks- sorry, I don't get it. Why would white spirit break down pencil marks. With respect, it might be the case that you have previously used a "rag" that was sufficiently abrasive to remove the marks.

 

[johnny2007]

Back in the days when I used to spray MDF with 2K paints, technical support at Morrells told me to never go over 320G between coats. Their reasoning way that going for a higher grit would effectively "polish" the surface and impair the adhesion of further coats.

Granted that was 2 part paints, but I took it on board. A normal human should not be able to see score marks created by 320 grit paper if the surface is sanded with a decent DA sander using decent abrasives, and with the sander connected to a decent dust extractor.

Random orbital sanders are extremely effective, unfortunately , when used without efficient dust extraction, or appropriate abrasives, they will leave squirl marks.

I do still have some very high grade papers for my sanders, up to 2000, but I would only ever use them as a pre-polish before working up to 10,000 cutting compound. I have never used them, I don't need top end car spray quality, and frankly, I don't have the skill set or spray set up for that level of finish.

Apropos white spirit to remove pencil marks- sorry, I don't get it. Why would white spirit break down pencil marks. With respect, it might be the case that you have previously used a "rag" that was sufficiently abrasive to remove the marks.

Well, try white spirit or methylated spirit and check for yourself.
In between coats, the paint won't be totally cured, so you can go as fine as you want.
The next layer will adhere to the previous by "melting" abit of the previous coat.
In fact, if you're doing multiple coats you only need sanding before last coat.

 

[Deleted member 174758]

One day, I noticed that a cloth with the filler on it worked well. The cloth is so dry that grain swell is almost negligible.

That would work well for a painted job, but not for a clear lacquered job where there is any open grain on the timber, especially timbers such as ash and oak, or with a coarse grain structure which you need to retain, such as hornbeam. In those instances your abrasive would almost certainly act as a grain filler, which may not be desireable if you intend to either stain the timber, fill in a different colour to white, or where you need to clear lacquer and leave the pores open. In the days of French polishing I have seen oak finished where the timber was blue, but the open pores were filled with a filler which had been coloured red (example chosen to illustrate that grain fillers can be in contrasting colours). Not my personal taste, but very striking (it was an exhibition stand).

 

[Odds]

Only thing i'd add to all this good advice is using Wilko's Clean Spirit, rather than White Spirit, for stubborn marks. It's not so harsh.

 

[opps]

Well, try white spirit or methylated spirit and check for yourself.
In between coats, the paint won't be totally cured, so you can go as fine as you want.
The next layer will adhere to the previous by "melting" abit of the previous coat.
In fact, if you're doing multiple coats you only need sanding before last coat.

Point taken. I will try them, thanks.

I agree that if you are coating up, recoats do not require any sanding if the paint hasn't cured.

Oil based paints take up to 28 days to cure. Water based paints up to 7 days. Shellac based paints 3 days. 2K paints are possibly the fastest that I am aware of (thanks to the catalyst).

The first coat however does require sanding, particularly if painting something like MDF. When priming MDF, I sand back a hellava lot of the primer off. MDF is not as flat as the manufacturers would have you believe. Other than the fibre grain, the sheets have parallel sanding marks. I guess they run the stuff through massive drum sanders.



This site compresses images, hopefully the cropped image will let people see the drum sander score marks to the right of the sander. In the image I used Leyland Trade acrylic primer. It is the only acrylic primer that I have used that is a dream to sand. Most other acrylic primers clog my abrasives.

Getting back to sanding between coats. If the client wants a high gloss (oil based) finish on their front door. I do sand in between coats to try to minimise any tram lines (read: brush marks). For a higher end finish, I will sand the original finish, fill, prime/undercoat, sand with 180g, and refill and re-prime as required. Then undercoat a couple of times and sand that back flat, and then 2 or three coats of gloss (with sanding between).

When working with 2K paints, I sand between each and every coat. I want to build up the depth/thickness of the paint but to minimise any evidence of spraying. If my technique and set up were better, I might not need to, but it works for me and none of the interior designers/etc that I have worked for have ever complained. That said, I am not confident, or possibly competent, to spray more than a 20% sheen level.

 

[Deleted member 174758]

Please define what you mean by "normal" and "fine" sandpaper. In almost all developed countries sandpaper is defined by coat (open or closed), abrasive type (e.g.garnet, silicon carbide, etc) and grit number (grid size, although just to be different 3M use grit size in microns on some products - such as Trizact)