What grit sandpaper

[white_tail]

I am wanting to wet sand my last coat of resin on my hull, what grit sand paper is suggested for this?

[Woodchuck]

Why would you wet sand a final coat of epoxy? You want to have a good mechanical bond between the varnish and the epoxy and that requires some tooth... I would not use anything finer than 120 grit on a randam orbital sander. With 220 grit, I think it is too smooth. After you have a few coats of varnish on , then wet sand to get the high gloss finish, IMHO
CYA, Joe

[white_tail]

Sorry this is my first canoe and I thought that the correct term was to wet sand before the varnish. Sorry that I asked the question.

[Woodchuck]

There are NO dumb questions... You only learn by asking and then giving us old farts something to do...
CYA, Joe

[pawistik]

What's wrong with wet sanding?

Wet sanding will help wash away any blush, if it's present. Wet sanding also helps to keep the sandpaper grit clear.

I don't recall, but I probably wet sanded mine prior to varnish, and probably used a 120 grit or something similar. As I said, I don`t really remember so don`t base your sanding on what I might or might not have done.

Cheers & happy sanding,
Bryan

[pawistik]

I really like some of the tips offered from One Ocean Kayaks. In this one he deals with wet sanding, though doesn`t specifiy what grit: http://www.oneoceankayaks.com/Wshophtm/Shop13.htm. Perhaps that's part of the additional detail that Vaclav includes in a builder's manual that you get when you buy one of his kayak plans.

OK, a little more reading through Vaclav's shop tips found this page under the S&G section: http://www.oneoceankayaks.com/stitchglu ... sand13.htm. There he describes sanding to 180 grit.

There are a thousand different ways to build these boats that will turn out a beautiful and functional end product. Those who have built many boats have their own preferred methods which can be quite different sometimes. I built one cedar strip kayak so far and used methods from a variety of sources, including ideas/methods described in at least 3 different books, plus numerous web sites, plus inovation gleaned from the forums. I picked techniques that suited my situation and style best. All that is to say there are no dumb questions and usually there is no single correct answer.

Cheers again,
Bryan

[Woodchuck]

My previous comment was based on my thinkiing that the final wet sanding on the epoxy was to be done to get a super smooth finish. The most important thing is the "tooth" required to get good ahesion. The benefits of wet sanding to keep paper clean, etc. are true but you still need a surface with marks, grooves and pits for the varnish to flow into and get a good hold. These imperfections are very, very small but they are there nevertheless and that's what you need. If you want ultra smooth, wet sand your final few coats of varnish with 600 grit of more. IMHO
Again, Joe

[pawistik]

I guess my thinking is that grit selection is independent of wet or dry, though you are right wet sanding does seem to excel at achieving the ultra-smooth.
Bryan

[Glen Smith]

When I built my first boat in 2001, I sanded the hull (dry) with 80, 120 and 220 grit. I then wet-sanded with 320 and 400 grit (maybe finer, can't remember). It produced a silky smooth surface. I applied "Clipper Clear" varnish. It has gathered a few scratches over the years but the varnish has never flaked. Makes you think about the "tooth" that everyone says we absolutely need.

[ealger]

Each varnish manufacturer has their own advice about surface prep. HMG suggest 150 to 180 over bare wood and 180 to 220 on refinishing. Then 180 to 320 after the first coat is dried. Wet sanding is recommended.

Epifanes one part recommendation at their website is a little evasive. One FAQ answer to sanding grit speaks to "closing" the grain first after sanding with 100 to 120 grit. (I suppose one could say that epoxy over glass has closed the grain). At this point switch to 320 wet/dry.

In any event, read the manufacturer's recommendation.
Ed..

[sedges]

I wet sand the epoxy before the first coat of varnish with 150 grit. It does clean the hull really well. Seems to be a fine surface for the first coat of varnish. I wet sand with 220 between coats of varnish. I am not building fine furniture grade boats so I never use any of that 320 or finer paper wet or dry.

One reason that I started doing more wet sanding as I am getting closer to varnish time is to keep the dust in the shop to a minimum.