Sanding prior to varnishing

[Storyline]

I have now stripped the old varnish off our sapele faced ply and solid sapele trim in the aft cabin using the magic bahco scraper.

The surfaces are now smooth and need sanding prior to varnishing.

What is the most efficient sanding regime (in terms of grade of paper) to get the surface ready?

I have been told to use wet n dry. Does this mean that I should wash the dust out periodically or just tap it out?

Any other sanding tips most welcome - I have lots of it!

I am using the Axminster pad shown here (I think I need shares in Axminster) /forums/images/graemlins/ooo.gif

 

[NickiCrutchfield]

The most effective way I have found is to sand very gently through the grades as you would in any other application, but after lightly abrading the surface, wipe with a damp cloth. Leave it to dry whilst you do another piece/area and you will find that this raises the grain and removes any loose matter trapped in the grain. If you do this religiously you will produce a very fine finish indeed. I learnt this from a Swiss yacht builder in Tunesee who spent much of is time restoring Rivas and the like. His standards were high, but it took ages.
Nicki

 

[ctelfer38]

If you are down to the bare wood, use a medium/ fine grade wet'n'dry paper to prepare for the first thinned coat of varnish. A good way of detecting if you have sanded sufficiently is to frequently run your fingertips over the area being treated as your sense of touch will soon tell you if the surface is smooth or not. Ditto when you are using finer grades of wet'n'dry at the stage of applying subsequent coats of varnish. /forums/images/graemlins/cool.gif

 

[RobinBirch]

I find wire wool -reducing the grades as you go-very helpful. The very slight shaving effect of the strands tends to cut down the 'furry' bits sometimes left by sanding. The other useful things are abrasive 'nylon' pads (different grades) -checkout Screwfix. Wirewool and abrasive pads are particularly useful for shaped trims.

 

[lesweeks]

Wire wool - OK, but brass or stainless steel stuff only. If you use ordinary steel wire wool little pieces will fly and you'll be forever finding spots of rust everywhere and your next post will be how to get rid of rust marks from wood and fibreglass!

 

[Storyline]

Thanks all

Is P180 then P400 OK or do I need to go to P800 at the end ?

The varnish (Tonkinois) does not require sanding after the second coat is on.

 

[Seanick]

Don't go too fine. The Pardeys reckon 120 before first few coats. I used to think this was too coarse but now realise they are right. It gives you a mechanical bond, which on tinber like teak, you really need. if you polish it up too much it will come off in sheets in years to come, just when you have achived a good build up.
We always sand between coats if we miss the overcoating times, usually three days, adjusted for conditions. If you leave it longer you may not get any cross linking, or intermolecular bonding! (love that term!)

 

[Captain Coochie]

I worked down the grades to a 240 grit wet and dry ( dry ) and then cleaned the surface with pure turps . Then a 240 grit de nib (wet) between coats .