Sanding Black Walnut for Danish Oil

[spiderlane]

Hi All,

I'm new to the forum and indeed new to working with hardwoods (have done plenty of household softwood joinery like skirting/architrave/balustrades etc) and am looking for advice in preparing my first hardwood project for finish.

I've made a lamp base out of American Black Walnut and I'm very pleased with how it's gone so far. I'm ready to move on to finishing which is going to be Danish Oil.

I've sanded the piece down to 120 grit and removed all the planer marks/dings/blemishes etc and it's nice and flat. I've been testing the Danish Oil against an offcut, so I sanded this to 120 then to 240 and put the oil on. The finish looks wonderful but I can see light and long scratches in the wood which can only be from the sanding. In fact the 240 sanding seemed to show up the scratches which weren't really visible after the sanding at 120.

I'm assuming that this is because I've jumped from 120 -> 240 and the 240 isn't coarse enough to get rid of the scratches caused by the 120? Should I go through a 150 or 180 grit before the 240?

All advice gratefully received. Like I said I'm new to the hobby and I don't want to let down my first project at the finishing stage.

Cheers
Mark

 

[CHJ]

If the finish from your cutting tools is not good enough then you do need to sand through each grade, removing any visible scratches from the previous grade before moving on to the next.

The scratches are showing up because the fine dust produced by the finer paper is collecting in the bigger scratches.

Make sure you are sanding with the grain wherever possible, not across it, any rogue longtitudanal scratches tend to blend in better with the grain structure.

If you have a card scraper or a a piece of an old saw blade you can make one from, you may find that you get a better finish by scraping rather than sanding.

 

[spiderlane]

Thanks for replying Chas. I'll try working down the grits on another test piece and see what the effects are. Would 120 -> 180 -> 240 sound reasonable?

The planed finish wasn't great on the timber and I don't (yet) have a p/t so I was stuck with making the best of what I had. I have just got a scraper and am starting to get to grips with how to sharpen it.

Thanks again for the advice.

Cheers
Mark

 

[Crooked Tree]

120, 180, 240 will be fine. Do the last bit of sanding at each grit with the grain for the reason given above. Do use a sanding block so as to make sure that it is level and don't use cheap sandpaper. The expensive stuff even works out cheaper in practice.

 

[spiderlane]

Thanks for all the advice guys.

Just reporting back on the thread for future reference. Working through a 150 grit did the trick and it has come up very well indeed. I wet sanded with 600 grit after the 2nd coat of Danish Oil which gave a lovely smooth finish, although this did lighten the finish somewhat from the earlier coats, so next time I might trade the smoothness for the deeper lustre of the more open grained look.

I learned something else along the way - a P400 grit paper is not the same as a 400 grit that American users might expect. I hadn't realised that there was a difference between the ISO "P" grades and the "CAMI" designations which I assume more US woodworking sites refer to (especially at finer grades). http://en.wikipedia.org/wiki/Sandpaper#Grit_sizes

Every day's a school day

 

[riclepp]

Hi spiderlane

Why are you going down to 600????? I never go any lower than 320. But I could be wrong, but I think that 600 would be for french polishing or some finish like that.??

Regards

 

[spiderlane]

Hi Richard.

I sanded down to 240 before I started the finishing. I then put on 2 coats of Danish oil. Then I used the P600 to wet sand in another coat of Danish oil. What this does is to create fine dust which combines with the oil to form a slurry; this then gets pushed into the grain an fills it. The P600 is fine enough not to put any (visible) scratches on the surface. Once it's been rubbed in, you wait a while for it to start to dry then wipe off the excess.

What you get after this is a very smooth, grain filled finish which is very soft to the touch. It's a very nice finish, but, like I said, this process did seem to lighten the end result slightly.

Cheers
Mark

 

[mickthetree]

Hi Mark
I know this is an old thread, but do you have any pics of the finished result? I'm testing some finished at the minute and like the sound of the grain filled surface.

 

[spiderlane]

Hi Mick

I don't have any pics of the piece right now, but I'll gladly take some over the weekend for you.

Cheers
Mark

 

[mickthetree]

Many thanks

 

[spiderlane]

Here are a few pics. Apologies about the quality (camera phone), but you get the idea.

Cheers
Mark


IMG_2437 by markelane, on Flickr


IMG_2436 by markelane, on Flickr


IMG_2435 by markelane, on Flickr



IMG_2434 by markelane, on Flickr

 

[mickthetree]

Many thanks for putting up the photos Mark. It looks great!!

I did a similar thing with a shellac finish the other day, sanding back the second coat with 400grit then applying another coat. This gave a lovely surface which I finished with beeswax polish.

Great lamp.

 

[Tim_H]

Mark I like that a lot, beautiful wood and the brass inlay on the top is excellent.

 

[Leif]

Yes, lovely.