Stripping polyurethane varnish

[Spuddy]

A previous owner got a thick build up of polyurethane varnish on the tiller. As it usually does, the wood shrinks and expands but the varnish stayed rigid, flaked and tiller had black patches. Took my own advice and used broken glass while wearing leather gloves, however there's still nooks and crannies where it's stuck fast. I've slapped on some old B&Q paint remover which doesn't touch polyurethane at all.
Anyone got a suggestion for a magic potion that will soften it?
Wondered bout caustic soda? Not got the heat gun handy but can that work?

 

[William_H]

No answers so I may have a suggestion. Aircraft are almost always painted with polyurethane paint and when the time comes they have to use a paint stripper to remove it. (too reduce weight) I have seen it used. Very aggressive stuff need lots of PPE. I don't know what it is called but a call to any aircraft equipment supplier or PU paint supplier might be able to help. ol'will

 

[FlyingGoose]

Heat gun and a good scrapper will do the job . also small sander if your careful with a rough pad, found stripper the worst

 

[jwilson]

Heat gun and a good scrapper will do the job . also small sander if your careful with a rough pad, found stripper the worst

If it's two pack polyurethane a heat gun quite probably won't soften it enough to scrape before burning and blackening the wood underneath. Mechanical sanding is the only safe option.

At least on a tiller you only have a small area to sand - I once had to get old "failing in patches" two-pack varnish off a large area - teak coachroof sides, window trims, handrails, cockpit coamings, gunwales etc. This is why I never use two-pack varnish: I'd rather remove ordinary varnish even annually if needed (easy with light heat and scraper) and revarnish, than use two-pack which might last 5 years, but will be an absolute swine to get off once it starts to fail.

 

[Martin&Rene]

Nitromors and give it time to work

The various paint removers have all changed over the years due to health hazards and EU legistation. I once had to strip the paint off a racing dinghy and found it had 2 different types of paints on in alternate layers and each layer required a different Nitromors paint stripper.

 

[Daydream believer]

A carpenter's flat wood scraper held between both hands. Push hard with both thumbs to flex it slightly & draw it along the grain. Use a planer blade if you have a flexible one. Sharpen the blade to leave a slight burr to help the cutting edge.

 

[Old Bumbulum]

The key to using tools is to use the right one. Though expensive the Linbide scrapper punches far above it's weight (hehe see what I done?) and is very effective.
Shop-bought Nitromors nowadays is utterly useless, it simply doesn't work as the H & S dictators have made it so weak. A little searching on t'internet for stripper containing Methylene Chloride will turn up suppliers but you'll have to buy a 5 litre can which is costly. At room temperature combined with steel wool or a scraper it will work nicely.

 

[Daydream believer]

Sandvik version is nicer to hold & use & comes in a couple of widths.
Sill need a blade with a slight curve for flat surfaces though

 

[Spuddy]

Thanks all. Doesn't sound very promising with strippers (over). I've got cabinet scrapers and the replaceable blade types but also find that picking out a suitably shaped glass fragment works well for odd shapes.
I'll dig out the heat gun and try that.

 

[Sparrowhawk]

Thanks all. Doesn't sound very promising with strippers (over). I've got cabinet scrapers and the replaceable blade types but also find that picking out a suitably shaped glass fragment works well for odd shapes.
I'll dig out the heat gun and try that.

 

[Sparrowhawk]

I used a paint stripper called Paint Panther with a tungsten blade tool. Worked well. You need to scrape well down into the wood. Any remaining patches of old varnish will be a different colour when you apply a fresh coat.