Clogged sandpaper

[Huey]

Hi Folks,

I tried to sand the old spar varnish off the mahogany plywood cabinets and seat frames of my boat. All I get is clogged sandpaper. Does anyone have experience with some kind of chemical stripper that I might use? Something I can get at a hardware store.

Thanks
Huey

[ssor]

Hi Huey, there are lots of varnish strippers out there and they all work, but most require a lot of fresh air. Those that don't usually require a water rinse. You may have some success with sanding with mineral spirits or paint thinner as a lubricant for the sand paper. You still need good ventilation. Also scrapeing can work well if you are careful not to gouge the wood.

[LazyJack]

I've always done pretty well with a heat gun and scraper or putty knife in those situations. The residue left behind is easily sanded clean. Forget that technique, however, if the varnish doesn't blister and lift easily. You dont want to heat a spot so long that you discolor the wood. I've done that too!

[Steve Miller]

Wet sanding your varnish will pretty much prevent clogged paper. I almost never dry sand varnish.

[Wild Wassa]

Huey, I kind of think that chemical strippers should be the last resort on wood because of the residues that can be left. There are gel strippers and paste strippers and paste strippers that are backed with a sheet to exclude air and are then peeled off in one hit (after a calibrated time, testing is essential and the paste has had time set) such as 'Peel Strip'. Peel Strip costs $30AU sq m. and $30 for a test kit. Gel strippers might cost a dollar or two per sq m.

I like to rub 'much' sawdust into the gel strippers before the final clean up with soapy water, when used on metal or wood.

Even cold scraping without heat is a much better alternitive to using any chemical strippers on wood.

Linbide from New Zealand make excellent carbide scrapers, not fancy but pro. Consider getting a 50mm general purpose scraper and a 12mm corner scraper, the two compliment each other. The blades can be reversed for scraping when applying heat and they have double sided blades for the general purpose scraper and are 4 sided for the corner scraper. Have a look at an 'Oldfields' Painting Tool' if interested, the third scraper in the kit, for smaller curved shapes, like rails.

Warren.

[ 03-11-2005, 03:37 PM: Message edited by: Wild Wassa ]

[Bruce Hooke]

A few thoughts:

1. Like LazyJack, my first line of attack would be a heat gun.

2. Some sandpapers clogs more than others. Stearate coated sandpaper (typically it's gray or off-white in color) might cut down on your clogging problems.

3. Is it possible that what is clogging the paper is something applied to or built-up on top of the varnish? Maybe try cleaning the surfaces first with soap and water...

[Scott Rosen]

What kind of sandpaper are you using?

Norton No-Fil Champagne is the best I've ever used. It cuts like edge tool and lasts many times longer than the 3M products.

[paul oman]

My guess would be "sea salts" . Did you wash the surfaces down with water before sanding. Over years the 'minerals' can condense/evaporate in your cabin surfaces. These would clog your sandpaper....

paul oman
progressive epoxy polymers

[ErikH]

How much varnish? if you're trying to remove 20 bad coats I'd scrape first...

[Charles Burgess]

That is why I use tongue oil instead of varnish for brite wood finishing.

Stay away from chemical paint strippers.

Clogging sandpaper could be indicating that you are using too fine of grit sandpaper.

[Huey]

I tried the heatgun and it worked great! There must have been 10 coats of varnish but it peeled right off.

Thanks for all the advise.
Huey