Dull spots on shellac over BLO on blackwood

[cor55]

Hi all, I'm finishing a dining table with ubeaut hard shellac. Wood is Blackwood, and I put a coat of boiled linseed oil on the wood that sat for five days before shellacing. The finish came up like glass, really amazing, but I had trouble with 4 patches of dull spots as big as my hand where the shellac just would not gloss up.

I've sanded back the dull spots, put hot water on them to maybe remove the excess oil, (they seem a bit oily, but the rest of the table took the shellac perfectly??) but I cant get them to the same gloss finish as the rest of the table.

I'm about to sand back the whole thing and refinish again, but I'd like to know if any of you have come across this issue and if so what might be the cause and remedy. I thought it was the linseed oil in those patches of wood reacting with the shellac, but . . .dont really know.

Also, as I want to darken the wood a bit before shellacing, so what oil might be good to use besides the blo? Or if I use the blo again, any suggestions of what to do so it dries or cures? I love the way the blo darkens the wood, and it looks really stunning under the gloss of the shellac, but if I have to deal with this issue I might have to just shellac the wood without any oil and have a lighter colour to it, but that's the last resort.

Any help would be appreciated.

Corey

This it the table with blo, before shellac

photo 4.jpg

[cor55]

I should mention that Im applying the shellac in a french polish way, with a rubber. Also, the blo was tipped onto the wood, flooded. Mayby I just put too much on. Would it be better if I just rubbed a thin amount onto the top before shellacing?

Thanks

Corey

[fineboxes]

Couple of things spring to mind, when French Polishing I have only heard of and used Raw Linseed oil as BLO has a drying agent not sure how that would react with French Polishing. The Idea of Linseed oil is to act as a lubricant for the rubber as the last stage of the polishing process is call Spiriting Off when the rubber is wet with just spirit the idea being to remove all the residue oil so if it has dried can't see how that can happen.

Another possibility and more likely is you have rubbed through the polish and burnt the dull areas. Best was to repair this is every time you walk pass give the dull areas a quick pull over with a charged rubber (one or 2 strokes only) this process CANNOT BE RUSHED, and may take a couple of days to rectify.

I would say on average every French Polishing Class I have run at least one student has this problem and for the life of me I don't understand why this remedy works but it does. All of a sudden it will POP and the gloss will match the rest of the table. BUT BE PATIENT rushing it will exasperate the problem I know 'cos I've tried

Give it a try before you redo the entire table, it could make it easier.

Try rubbing surface of bear timber before polishing with Raw Linseed, use it sparingly and make sure to rub off all excess, see if it makes a difference next time.


Cheers

Steve

[cor55]

thanks steve, i appreciate the advice

i've already stripped it back and wiped it with hot water and metho to dry off the blo and will sand it back

still thinking about how i'll go about it - probably wipe a very very thin amount of blo onto the wood, or none at all

I didnt use any oil during the polishing process, and it worked out really really good. If the dull spots happen again I'll do as you suggest to see if I can gloss them up

i did read that french polish over blo was ok, and as 95% of the table was perfect, i just think that these spots were some kind of dense or oily wood or god knows what

thanks again

corey

[cor55]

I found this info:
French Polishing

read the excerpt:
photo.jpg

[ubeaut]

G'day Corey - You said"i did read that french polish over blo was ok," but I guess you didn't actually read this bit:

It should always be remembered that linseed oil, while indispensable, is the greatest enemy of the French polisher and the use of this agent must therefore be regarded as a necessary evil. The oil should be employed as sparingly as possible, since if too much is used it will work through the coating of polish in the form of sweat, thus spoiling the appearance of the work.

There's your problem in a nutshell. Raw linseed can be used very sparingly prior to polishing, the reason for this is partly to darken the timber somewhat, but mainly to make the grain pop ie: to bring out the very best of the timbers depth and inner beauty. Flooding the surface with the oil is a massive no-no. To get rid of the oil use lots of mineral turpentine and lots of clean dry rag to wipe it off with.

I wouldn't use BLO under or during french polishing.

If you are using Hard Shellac and wish to use an oil to lubricate the polish whilst rubbing use our FoodSafe Plus which is a heavy medical grade paraffin oil. Linseed and most other oils don't seem to work anywhere as well as the FoodSafe with Hard Shellac. You may need to cut it slightly with a little mineral turpentine if you find it a bit heavy for use with the rubber, but it does work really well and another advantage is that it is a non drying oil.

This means you can walk away from a job and come back to it a week later and pick up where you left off, because unlike linseed it won't skin on the surface. So you don't have to remove the oil at the end of a session.

Hope this is of some help.

Cheers - Neil

[cor55]

Thanks for your time to respond Neil

Let me just clarify so you dont think I'm an idiot - I said I read it because I read it elsewhere on the web. That article I found only after looking for an answer to my problem - I wish I had read it first. There is a lot of stuff out there that you dont know is right or wrong until you have the experience of it.

Your product I have found to be excellent, and I got it to a mirror finish without using any oil as lubricant. After that the 'sweating' began.

I've stripped it back and used boiling water and metho to try and clean up the blo, hopefully it worked. I will start again, and will let everyone know how it finishes up shortly.

Corey

[ubeaut]

G'day Corey - Use mineral turpentine to help clean up the BLO along with lots of clean rag to wipe the residue away. The metho will only serve to drive the shellac deeper into the timber but won't help to remove the oil and as the oil is pretty much water resistant the hot water probably won't do a lot towards cleaning the oil away either.

The boiling water may also be doing more harm than good. You could wait for the water etc to dry then lay some clean soft rag or even some good absorbent kitchen towel over the top of the work and use an iron to melt the oil out of the timber and draw it into the rag or paper. This will also help to dry out the timber a bit. Waste of time putting more shellac or anything much else on to timber with a high moisture content as it will bloom (leave a cloudy surface on the work)

Hope this helps a little.

Cheers - Neil :

[cor55]

Thanks Neil, you've got me thinking I'm back in the deep end . . .

I've bodied up the shellac and all appears well at this stage.

I did let the table dry out before I started finishing, so I'm pretty sure blooming wont be an issue. I'm hoping that enough oil was removed to stop the sweating happening again. The wood did look considerably lighter than when the blo was flooded on it, almost like bare timber again.

I'm going to keep going with the finishing process and keep the fingers crossed. Worst comes to worst I can scrape it off and start again - gotta keep ourselves busy right? It was pretty easy scraping it off with some metho on it then used a plane blade. Took about an hour.

Will keep you posted, and I'll get some photos of hows its looking up soon.

Thanks again for your advice.

[cor55]

Hi all

I re-bodied the top with shellac and was left with 2 dull spots. I stripped back these spots and used turps to flood and soak up with clean rags, then dried.

But these two spots are still there after bodying up again and sanding then using the rubber, and I've even painted the area with a brush which seems to be successful but after a while the area is dull again, like the shellac is just vanishing into these two spots. I dont get it. I've put a lot of shellac over these areas, but when I use the rubber to body up, the surrounding area goes glossy but these spots remain matt.

I'm going to sand it then try Steves advice of patiently passing a rubber over these areas, but anyone got any other suggestions as to what is going wrong?



Corey

[jimbur]

You've had excellent advice so far. Don't touch it for a week or two. If necessary get someone to tie your hands behind your back.
Come back to it when it's dried out and resist any urge to flood. French polishing is at its best when small quantities go over a large area.

[cor55]

Thanks Jim, looks like this is going to be a test of patience.

[cor55]

After patiently applying the shellac over the last week, I finally have a finish that, although not perfect, is pretty good for my first dining table surface. Please see the photos . . . and thanks to all those of you for the advice and encouragement.

photo 4.jpgphoto 2.jpgphoto 3.jpgphoto.jpgIMG_1156.jpg

[jimbur]

You can sit back now Corey, the onus passes on to the users. Polishing over the next hundred years or so will develop an excellent patina.
I imagine that in a month or two you'll will be hard pressed to worked out where the problem area was.

[cor55]

Thanks to your advice.

Is there any product I should use on the table, like a wax or something, to protect and enhance the shellac finish?