Varnish help!

[NUTMEG]

No, that's alright I will do the work myself BUT I could use some advice.

Got the spars in my lean-to except the boom, that's lying up the stairs, and have removed all the hardware. Got some cabinet scrapers (and a honeing tool) and started scraping this afternoon. The varnish comes of in little fluffy bundles, and leaves a matt finish. Do I need to go right back to the wood or can I recoat this matt finish which I think is some remaining varnish layer?

No rotten wood or flaky bits to worry about.

And where can I get new thumbs from to replace these painful ones!

 

[VicS]

No, that's alright I will do the work myself BUT I could use some advice.

Got the spars in my lean-to except the boom, that's lying up the stairs, and have removed all the hardware. Got some cabinet scrapers (and a honeing tool) and started scraping this afternoon. The varnish comes of in little fluffy bundles, and leaves a matt finish. Do I need to go right back to the wood or can I recoat this matt finish which I think is some remaining varnish layer?

No rotten wood or flaky bits to worry about.

And where can I get new thumbs from to replace these painful ones!

Normally I would only sand sound varnish to give a key for the new stuff.

Every now and then, esp if it starts to flake, it is necessary to strip back to bare wood and start again , maybe starting with a thinned coat if recommended by the manufacturer but in any case about 5 coats un-thinned.

( I suppose I should add , someone will if I don't, that you cannot as rule apply a two pack over a single pack , but I am sure you knew that anyway)


Hook type scrapers eg Bahco and Sandvik are good for removing varnish

 

[NUTMEG]

Thanks VicS, so if I have this right, take the gloss off, either scrape or sand, and recoat. No need to get back to bare wood. That will make it easier! I read somewhere here that black bits can be hidden/removed with Oxalic Acid. The bowsprit a OK but the gaff needs attention.

 

[VicS]

Thanks VicS, so if I have this right, take the gloss off, either scrape or sand, and recoat. No need to get back to bare wood. That will make it easier! I read somewhere here that black bits can be hidden/removed with Oxalic Acid. The bowsprit a OK but the gaff needs attention.

Look at the product data sheet for the varnish you intend using. The following is a extract from one of International's data sheets

PREVIOUSLY VARNISHED WOOD
In Good Condition Clean with thinners. Sand smooth with 280-320 grade paper. Remove sanding dust with thinners.
In Poor Condition Remove all previous coatings.
Apply a minimum of 3-5 coats. Sand every 2-3 coats, using 320-400 grade paper.* Remove sanding dust with a dust
wipe.
BARE WOOD Sand smooth with 80-180 grade paper and then 280 grade paper. Remove sanding dust by brushing,
dusting and wiping. If wiping with solvent then allow to dry completely before applying the first coat.

washing with water is a good way of removing sanding dust. Obviously don't make too wet and allow to dry thoroughly before proceeding.

Dust is the enemy when varnishing and dogs hairs :wink:

I have never personally use oxalic acid for restoring colour to timber but it is a well known use. See http://www.agwoodcare.co.uk/prod/oxalic_acid.html

 

[tillergirl]

You will need to go back to bare wood to use oxalic acid (wear some gloves). May need a few goes but it works.