boardroom table finishing

[SJD]

Hi, First post here - looks like a great forum.

I'm after some suggestions for finishing a boardroom table - going for a piano gloss.

- veneered, 3 x 1.2m approx - (yes veneered- but makes for good practice and a good project)

Not bothering with the legs (still in good nick)

- Stripped, sanded back to bare wood (or rather, bare veneer)

- Now staining it dark mahogany - using carbots interior stain (oil based) had to mix with feast watson black pigment to get the colour i desired. All going well so far.

Could be a little darker though, the darkest stain (reddish based) carbots sell is australian jarrah - nowhere near dark enough!

Was thinking of using carbots carbothane for the finish - (gloss) any suggestions?

I have done this before - but as I don't have a dust free environment - have to sand up to gloss finish

- As I understand it (jump in here) but with these types of finishes (poly) the last coat is meant to be left- job is done.

however- the dust coupled with the large surface area dictates that I have to sand / polish it to gloss

what I did last time (which gave a fair result) was:

- 4 coats carbothane - light sand between each coat

- levelling w/ 400 (dull, consistent scratch pattern) followed by 600/ 800 / 1000 / 1200 / 1500 / 2000 (dry sand/ random power sander)

- then used an automotive rubbing compound (actually a plastic polish) and hand buffed it

-smoother than glass! BUT - felt it could LOOK a little better however

- is this is normal (ha normal!) way of doing things? are there other methods / materials that will give me a piano gloss finish? hard finish oils / shellac / shellac / wax? comments on any parts of my process would be appreciated

- Cheers for your help - SJD

[durwood]

Can you answer a couple of questions?

Are you brushing or spraying the finish?

If spraying why are you rubbing it back so much? (besides the dust)

Why are you getting a lot of dust -(where are you painting it??

Can you paint it outside?

[echnidna]

Stay away from shellac on a boardroom table.
If they spill their booze on it, it will play havoc with the finish.

[SJD]

Hi,

Thanks for the responses

Probably safe to assume it will have drinks on it - shellac is out then

Brushing it on -

I've found this works just fine (not that I can compare to a spray job - never done it) if you're careful

Its in a shop near a busy road with trams

Old building / open roller doors open when work is done - (closed while drying however)

Probably could do it sunday (have before - but building is just plain dusty at all times!)

Actually - dust really isn't that bad - but noticeable

However the gloss after drying looks really cheap (wet look) compared to going through the whole process - so I'd prefer to polish it anyway

Cheers!

[durwood]

I havn't enough time to answer fully at the moment but will soon. Don't know if I can solve your problems you probably need a better invironment and more equipment to get past where you are but you are doing some unnecessary processes.

[SJD]

Cheers durwood, looking forward to your suggestions

[durwood]

The forum won't allow me to post my response, maybe its too long? I will see if I can email you.

[astrid]

vacume cleaner and close the doors, men, sigh,
astrid

[durwood]

I emailed SJD 3 days ago but as there has been no reply its possible he didn't receive the email.

Its just occured to me after viewing some other posts that my response may come through if I split it up so I will try to post it in two parts here goes!!!

First : yes the polyurethane finishes are meant to be applied and the result is what you get.
So if you brush it and the brush marks show then you are supposed to accept them as the material isn’t really meant to be then flattened and buffed to a shine. Usually buffing/compounding is not done on furniture type products because it is messy and the finish if applied properly is usually acceptable as an interior finish. It would be expected that you had available equipment and skill to enable you to upgrade the finish past what a home handyman may do if that was needed.

If you want up the anti and make it a piano type finish easily other methods are usually undertaken.
<O</OPolyurethane dries so hard you will have a hard time working the surface after a week. Do any sanding and polishing as soon as you can after it has set. That will depend on the temperature and what product you have used (usually 24 hours in normal temp ) at around 24 Degrees.
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The high gloss piano finishes were originally done by applying nitro cellulose lacquer and then treating it like French polishing using a pad to smooth out the peel or any scratches or other faults.
It could also be buffed with a compound or other materials and finished off with a dry lambs wool pad on a buffing machine with corn flower. Now they use Acrylic Urethane 2 pack enamel and cut and buff as would be done on a motor vehicle. These paints are designed to be polished if needed where as household versions aren’t. So you are going to find it difficult to produce such a high gloss finish easily with the kind of material you are using. If you used automotive paint you could brush it on even though its usually sprayed it could then be cut and buffed easily to a mirror finish. You would have to do a test to see it didn’t react with the oil stain as the solvent is strong. It could be placed over your polyurethane as the final coat no problems.
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[durwood]

You can probably reduce your dust problem if you wet down the area around where you are working to lay the dust. If you think it is dropping down from above then you could also place a plastic sheet above where you are working or as you are only brushing make an enclosure like a booth to work in. Closing it right up will trap the fumes given off when it starts to dry so you may need to see whether its worth the extra trouble and add a fan and filters pads to catch the dust entering the area as well as wearing a good mask. Rubbing it dry will cause more dust to be in the area.
<O
You state the dust isn’t so bad so if it’s not the main problem then it must be the brush marks finish you are getting? How good is the brush? If you haven’t already invested in a good quality pure bristle brush. As it’s a table top( Large area I presume) then a nice wide one 4” or more.
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Rubbing the finish dry is not normally advised unless you have a good dust extraction system on your sander the dust is as poisonous as the materials being sprayed. Before you paint each coat use a suitable tack rag. to wipe the surface.
<O
If you rub the coats between each other don’t use anything courser than 800. It will flatten and remove any faults and provide a good surface for the next coat. Any finer is unnecessary as the following coat will well and truly fill the scratches left but courser grades may leave scratches showing, wrecking what could have been a perfect surface.
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[durwood]

You are making a lot of extra work for yourself with your rubbing technique. If you have put on a reasonably smooth coat of clear starting rubbing with 400 is unnecessary.
If this material was being put on by a tradesman he would be using far finer grade abrasive paper especially on the final coat to produce a glossy finish.
<O
It should be flat enough after the final coat is dried to start at 1000 or more. By starting at 400 you will quickly rip off the brush marks and dust but you have put into the surface really deep scratches. Abrasive paper is basically a file.
<O
This is what is happening. : ( this is an exaggeration but you should get what I mean. )

You rub with 400 the scratches are say 400 parts deep You then rub with 600 so the scratches are only 350 deep the 800 replaced the scratches with 300 deep ones ( so far you have taken off 100 parts of thickness of the coating. You continue to 1000, then 1200 then 1500 then 2000. Now you have taken 300 parts off the coating and have scratches in the surface which still have to be rubbed down the depth of the scratches left by the 2000 with a compound paste which probably equals 20,000 grit. If the poly is rock hard it can take hours with a buffing machine let alone hand compounding.
<O
You not only rubbed a lot of your surface coating away but could have saved lots of elbow grease if you had started with 1500 and then went to 2000. A machine buff would get the same result you are getting in about a 10<SUP>th</SUP> of the time and you could then use some form of polish or wax to gain an even better result. You would also get a far better result if you rubbed wet with the aid of soap as a lubricant. ( sunlight soap, not perfumed soap). You do this by hand with a flat rubber block, means you are rubbing by hand as you can’t use most electric sanders but you will save on the hand compounding. When you rub the surface will go flat and any glossy marks left means they are low and more rubbing in that area is needed.
<O
As you are using fine grades (1500-200) I presume you are using silicon carbide paper. If you are you will leave deep scratches compared to the same grade in Aluminium oxide paper. The aluminium Oxide will also last a lot longer before it has to be replaced by a new bit of paper. It’s a brown paper rather than black, costs more but it well worth it.
<O
This rubbing/buffing process is after sanding to get a good shine will not need lots of elbow grease but if you don’t use a good compound may result in a poor finished result which you say you are tending to get. I’m not sure what you mean by using an automotive plastic polish you need a 2 pack Acrylic Enamel material. This is entirely different to other compounds used to polish/buff paint work it has in it abrasives and solvents which cut and revitalise the sanded finish into a wet and glossy surface. The old compounds used on lacquers leave a dull scratchy finish in comparison.
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[MacS]

Just a thought, whenever rubbing or polishing poly, you need to wait longer then many other coatings.

That may have been your problem, you got good advice here, but if the poly is not ready to be rub or polish it never comes out 100%.