Varnish removal tools and techniques

[stevd]

Hi All,

My next fun job is to remove all the very dark varnish from my boat interior, to refresh with a much lighter colour in the attempt to give the boat an airier feel. ATM it is very dark and horrible. This means that I have to do it all :-( from the fiddly little bits to the large area bulk heads. What techniques do most people use. Do you use a heat gun and stripping knife, chemicals, belt sanders, oribital sanders.

Basically I dont want to spend a fortune on getting all the wrong tools, but I also dont want to take forever doing it.

I am look for the pros and cons of different methods. I am thinking a belt sander would be great on the bulk heads as they have dust bags attached, but not much use elsewhere.

AS heat gun looks effective, but very slow work.

And chemicals seems very messy, with the added risk of getting it on to GRP.

So, from peoples experience. Whats is the quickest and easiest way to do this?

 

[LittleShip]

I use this for Anti foul, paint and varnish....

http://www.gelplane.co.uk/proscraper/product.asp

Nothing else comes close.

You stated that your interior was dark, be aware that if you want to get it lighter you will need to remove all the old varnish from the grain, that may cause problems if your working with ply. Dont and I'll repeat that, DONT sand through the top layer.

Tom.

 

[rob2]

Agree with the above - a belt sander is great for fast work on solid wood, where you have enough material to correct errors, but will go through the top ply of your bulkheads in no time! I'm afraid the words "quick" and "easy" never go with varnish stripping. The best method really is scraping, possibly helped ny softening with chemical stripper.

Rob.

 

[stevd]

Thanks, I never thought of that. So a hot air gun with scrapper for the bulk top layer, and then chemical stripper for the grain then?

 

[causeway]

Why not just paint a few areas/panels white? Would save you a whole lot of work and would freshen it up no end.

 

[Poignard]

Nitromors is very effective on traditional varnishes (but very expensive).

You must take care to keep it off other surfaces.

And it stings your hands, so rubber gloves are worth using.

I don't suppose the fumes are very good for you so leave the hatches open.

 

[Tranona]

You will probably have to experiment with different methods or combinations depending on what the current finish is. Solid wood is normally quite easy to do but flat panels are a problem, partly because of the large vertical areas and partly because the face veneers are usually thin so easily sanded through. Keep sanding to a minimum and avoid belt sanders unless you can get the panels out and lay them flat - for example cabin soles. You don't need a lot of expensive equipment as it is mostly down to hard work, but good sharp scrapers are essential, sanding blocks for large areas and maybe a detail sander for awkward corners. Once you have the coating off you may well need to do something to ensure an even colour so wash with dilute oxalic acid to clean the grain and then perhaps use a wood dye if you end up with mismatched areas. Again you will have to experiment. Avoid high gloss finishes and use a satin or "rubbed" finish as it hides the inevitable imperfections and imparts a warm feeling.

 

[stevd]

Thats some good advice. I already have a tub of Oxlic acid so I will give it a rub down with that. I wouldnt have thought of that! There is so much to do on it!! It is going to take forever and a day I think!!

Screwfix have 4l Nitromors for £38 so I better invest in some of that.

So it is just a heat gun that I really need then, as I already have a good scrapper and a small handheld detail sander. For the sanding parts, what grit paper is best?

 

[jac]

Having done a fair bit of varnishing over the years and made some mistakes my top tip -

DON'T TRY AND CUT CORNERS

Varnishing looks great when done properly but any imperfections are highlighted.

So.

Do not use powered sanders or heat guns as they run the risk of damaging the wood. (Maybe heat gun if really careful and lots of coats.
Use chemical stripper, (Nitromors) and skarsten type scraper with new blades (lots of new blades)
When all off, sand with wet and dry, about 180 then 320 used dry.
Then lots of thin coats following manufacturers instructions, sanding any imperfections out between coats. Personally if going for good finish will sand down wet with no more than 320, then wash off then give a key then varnish. After 6 or 7 coats then you can start using even finer grades.

Finally, make sure the brush hasn't been used for anything other than varnish and is old quality and make sure the surrounding area doesn't have loose material around such as dust.

If doing the entire inside as well, I would take a decent Hoover to remove the dust etc from as much of the boat as possible once sanded as it will settle so a combination of Hoover and washing it all out will prevent the "arggghhh" moment.

 

[Tranona]

I use "production" paper which I buy by the metre off a roll and mostly use 120, 180 and 240 and sometimes 60 for fast removal, but its a bit fierce for cabinet work.

 

[maby]

If the worst comes to the worst, get some veneer and recover the interior - it is surprisingly cheap provided you don't insist on anything too exotic.

 

[jwilson]

On ply panels, where you have to be ultra-careful not to go through the thin top veneer, a cabinet scraper is good, used carefully after a gentle warm up from a hot air gun. It's just a square or rectangle of thin tool steel. http://woodgears.ca/scraper/ shows how to use one.

Don't underestimate the time the job will take. I don't think there is anywhere in most yacht interiors where power sanders are going to be much help, and they have the potential for a lot of damage caused.

White paint on the bulkheads, and just sanding and varnishing the solid trim edges is so much faster.

 

[viva]

The seminal work on varnishing a The Brightwork Companion recommends the following methods in descending order of preference DOD is Degree of Difficulty

1 Heat gun DOD easy efficient and cost effective
2 Chemical DOD requires patience to get results -costly messy and time consuming
3 Dry scraping DOD requires a sure hand. - not a method for amateurs
4 sanding DOD not a smart way to strip - only as a last resort

Whatever you do don' t use a belt sander below. They are too aggressive and one lapse of concentration or a slip ...

 

[Appleyard]

Warning!!!!
Nitromors have changed the formula ,and it no longer contains Methylene Dichloride (SP?) which was the active ingredient.This was because of the carcinogenic nature of the chemical.

IT IS NOW USELESS!! Believe me.

A furniture restorer friend put me on to another paint stripper called Paramose. Obtainable from specialist decorators merchants or online. You need to state that you are using it in a professional basis,otherwise hey can't sell it .IT WORKS.

 

[hartcjhart]

get a pane of glass and cut strips of about 6''x2'' to use as a scraper thats what a cabinet maker tought me to do when re-french polishing a table,draw the glass gently towards you

 

[nigelmercier]

I use this for Anti foul, paint and varnish... http://www.gelplane.co.uk/proscraper/product.asp Nothing else comes close...

Amazon UK: http://www.amazon.co.uk/exec/obidos/ASIN/B002DKYKU6/dolcetto-21

 

[billcowan]

We had to strip a lot of polyurethane varnish,
nitromors, even the original stuff didn't work.
hot air gun was toiling and danger of burning the wood.

solution? get this; wallpaper steamer - brilliant.

use the small shoe, the one for doing around light switches etc, hold the steam on for 6 seconds, wipe off the varnish with a sharp cabinet scraper or triangular shave hook working with the grain. (must be sharp or you will tear the grain of the wood)

The steam gets under the varnish and lifts it off, it really gets it out of the grain much better than when using a hot air gun.
wood dries almost instantly afterwards.
when completely dry, sand.

Best varnish I have tried: Osmo polyx oil inside, Osmo uv oil outside, better than Decks oil

 

[AntarcticPilot]

I've just spent a few days doing exactly this job on veneered plywood on my Moody 31.

In the past I have used "mouse" type electric sanders, but the problem with using them in the cabin is that they create very fine dust that gets everywhere. Also, they won't get into awkward corners, which abound on most boats! Ideal for locker doors etc. that can be dismantled and worked on at home or outdoors; not so good for bulkheads or other fixed woodwork.

So this time, I used a SHARP draw scraper (similar to this http://ecx.images-amazon.com/images/I/41n7a5RMoJL._SY355_.jpg) and some cabinet scrapers. I found it essential to keep the scrapers sharp, using a diamond hone quite frequently. I also took the corners of the draw-scraper's blade, to avoid the blade digging in. I used an ordinary (sharp!) shave-hook to get into difficult corners.

USed carefully, this gave excellent results, and it didn't take too long. It also left a surface suitable for immediate varnishing (the final scraping used the cabinet scrapers). I didn't find it necessary to use either hot air or paint-stripper; I am pretty sure that neither would actually have made much difference to the time taken or the quality of the result.

This time I didn't use Oxalic acid, but this certainly helps to remove dark stains and lighten the colour of the wood.

 

[nigelmercier]

I used a SHARP draw scraper (similar to this)

Fixed image, links below...
http://www.amazon.co.uk/exec/obidos/ASIN/B001C7QLEE/dolcetto-21
http://www.amazon.co.uk/exec/obidos/ASIN/B000MPQDCW/dolcetto-21