Am I "Burning" the wood with my sander?

[crash76]

I'm trying to sand back my redgum slab to start putting on the varnish.

I started using a sheet sander, which wasnt doing a great job, so I brought a belt sander.

It now looks like I am possibly burning the wood with the sander, as there are black marks here and there (i saw these with the sheet sander too). They almost look like smudge marks, not the black within the grain. Am i burning it with the sander, and should i just keep going with the 60 grit paper?

Also there looks like corrugations, or tiger stripes over the wood. Is this just the normal charecteristic of redgum or can these be sanded out too?

regards

Crash.

[nrb]

Any chance of a Pic crash?

[DJ’s Timber]

They almost look like smudge marks, not the black within the grain. Am i burning it with the sander, and should i just keep going with the 60 grit paper?

Also there looks like corrugations, or tiger stripes over the wood. Is this just the normal charecteristic of redgum or can these be sanded out too?

Is the redgum dry?

Do the corrugations/tiger strips look the same as what is in my avatar? If so then yes it is a characteristic of redgum.

Put up a pic if you can.

[crash76]

The slabs have been kiln dried, as well as air dried for a further year, so should be dry.

I'll try for a pic if i can, but dont hold your breath, as not too good at uploading them.

The tiger stripes kind of do look like your pic nrb, but i can see the grain in yours, mine doesnt quite look like that. Maybe it will come up once i coat it.

I'll try for some pics now though.

thanks.

[crash76]

I have tried to add a few photos, hopefully it works, and gives an idea of what i'm talking about!

[DJ’s Timber]

The grain will show up better once you've gone through the range of grits and then once you apply a finish, the grain should show more, my avatar is just a piece that has been through the thicknesser and a bit of water splashed on it.

If you really want to make the grain stand out, it might be worthwhile experimenting with some off cuts or the bottom with some different finishes, maybe apply some shellac prior to coating.

I can drop in and look at it and advise if you like. Warranwood isn't far and is on my way to my parents in Templestowe.

[DJ’s Timber]

Ok, can see you've posted some pics whilst I was doing last reply.

Looks like you might be a bit heavyhanded with the sander, are you pressing it into the work or guiding the sander?

[crash76]

here are some with the wood wet down.

[rod1949]

It looks more like toeing and heeling with the belt sander, which you are not the Lone Ranger, we've all done it and still do it. To master a hand held belt sander is a skill in its self.

Stop using the 60 grit (you'll be suprised how deep the scratches of the 60 grit will be) and start using 100 grit and finer and then revert back to the orbital sander with 120, 180 or 240 grit paper. Good luck.

[nrb]

Rod1949 is right the belt sander can be a beast,worse if you only use it now and again,I only use mine for real rough stuff.
The orbital sander is the way to go.With what you have shown us it looks like you will have a great finish.

[crash76]

So do I stop using the belt sander, and just use the orbital sander with 100 grit paper? i initially only wanted the belt sander to get the saw marks out of it, which i have done so, but now i have the smudges and tiger stipes! its not an expensive belt sander, so happy to get rid of it, especially if its causing prolems.

Might be a silly question, but how long do i actually hold the sander in one area/use in an area? I currently just kind of slide it backwards and forwards along teh grain. and how often am i supposed to change the sanding sheets.

And will the orgital sander get the tiger stripes out?

[crash76]

Could the tiger stripes be something called "fiddleback" and just part of the wood?

[DJ’s Timber]

Are you in a hurry to get this done? Can drop in and advise.

Belt sanders work better travelling across the grain and slow advances along the grain rather then following the grain. Try sanding one of the darker areas by hand to see if it goes away, you can't burn it by hand sanding. They must be moving all the time, never keep it still in one spot. Change the belts/sheets often, as soon as it shows that it is no longer cutting without putting pressure on it.

And no, you will not get the tiger stripes out, it is a natural feature of the timber, is in fact often sought after, as it is quite speccy when done properly.