I have read that this is an effective technique. More specifically, the
book said to use the type of thinner/cleaner for the finish you are sanding
as the lubricant for waterproof (Silicone carbide) sandpaper. I am not sure
that I can bring myself to do it without being re-assured.
What would be the technique to do this. Do you need to rinse it off? Would
you rinse that with straight thinner, or water, or a dry rag, or any
prescribed order of any or all of the above? Does it require a wipable
surface (e.g. tabletop) to squeegee off?
Assuming the following (another reason) were true, is this safe?
Assuming the following (another reason) weren't true, is this safe?
I think I just thought of another reason why not to. I am doing drawers.
This may trap slurry, swarf, whatever you call it, into tight areas you
can't scour, squeegee, gravity won't work, etc.. This trapped thinner may be
harmful over time, regardless of the other answers.
BTW, all the drawers now have an "air tight seal" around all meeting corners
now that the bottom and sides are poly'd to one another after the first
Also, I have and will be using a tack rag to clean it. I foresee spotlessly
clean corners regardless in my near future. Recommendations?
I'm using Minwax Spar Satin Poly.
I am going to be sanding with 220 (Silicone carbide) sandpaper anyways.
Just wondering if MS as lubrication is safe, and now, in this drawer
The rational behind this is to avoid leaving a non-compatible residue
on the finish, while getting the benefits of wet sanding. If you use
water, on a oil based finish, you might trap
some in an imperfection somewhere.
But before you try mineral spirits, consider the down side. It is
flamable. You should not be doing this inside a shop, unless you have a
professional finishing room. You should have a fire extinguisher handy,
and be wearing gloves. You also should not be using it if it will
soften the finish you are sanding. If you try laquer thinner to sand
laquer, you end up with goo. It is not a great rule of thumb. But to be
fair, mineral spirits is not near as flamable as laquer thinner or
acetone. But caution is called for.
You do need to rinse, with mineral spirits, and let dry, and then use a
tack cloth. Water will work almost as well, but you do need to let it
dry a bit longer. That is the benefit of using mineral spirits. Mineral
spirits in it self will not leave a residue. And is useful for dewaxing
if a finish might contain disolved wax. Just do not use it inside.
The mineral sprits are as flammable as those which serve as a solvent in the
polyurethane, assuming that we're speaking of oil-based poly.
The rationale is that wet sanding keeps the finer grits cutting longer, but
they should be wiped and tacked thoroughly. Dry wipes ok, since the mineral
spirits evaporate rapidly.
Stearated open coat papers are available if you don't want full cutting.
The minimal soap that lubricates them dissolves in the next coat of finish.
Is there more than one kind of mineral spirits? I never could get it to
burn......years ago I needed to scrub a 10,000 ft concrete floor with the
stuff, had reasonable paranoia about igniting the place so I tried various
tests...flammable it wasn't, at least not with the expected normal
environment for the job. If memory serves me correctly even a propane torch
wouldn't light the stuff (will have to check that one out again).....Rod
Why are you using poly and spar at that on the drawers anyway? Is this for an
application. They will smell for a long long time and since it is spar they will
harden completely. Most people recommend shellac for drawers. Cheers, JG
Many people use thinners or water to wet sand between coats, but all you
really need to do is break the glaze. A red 3M pad will do beautifully for
this, with no lubricant. 0000 steel wool will work very well also, but it
sheds and you have to be very careful to remove all of the slivers before
the next coat goes on or you do a great decoupage job over them. I only wet
sand the final coat unless I somehow get some big globs of stuff like dust
or bugs in the build up coats. Small dust nibs can be left as they are in
the build up coats and simply knocked down in the finish coat, but small is
a difficult term to define. Typically, things like mosquitoes are too big
Okay, here's what I do. First off, I thin the poly. Maybe, about five
percent. The stuff is barely thicker than water, with the thinner. (I
swear, one of this days I'm going to try dipping a small project, rather
than brushing it on.)
I put it on quick, and LIGHT. I use as light a touch as I can and still get
It's more of a sealer coat, at this stage. I let it dry thoroughly, usually
overnight, and then sand lightly with 220 grit sand paper.
Then I apply a full strength coat of poly. Again, I don't fuss with it. I
apply it lightly as I can, since sags and runs are practically impossible
to remove. Another sanding with 220. It should be very smooth at this
Usually, I apply another coat. Again, it most dry thoroughly. However,
this time, I use 600 grit sandpaper. It doesn't sand it as much as it
It's going to take at least two coats, maybe three. Get use to the idea.
For sure, patience is not my strong suit. But dry means thoroughly dry, not
mostly dry. If it takes overnight, that's what it takes.
Do not fuss with poly. It flows together as it dries.
A couple of thin coats are always better than one thick coat.
That's my story and I'm sticking to it.
I am about to sand the first coat w/ 220 SC. It looks like good coverage.
It was easier than I thought to control thickness, flow, and globs. It is
great. I am pretty good w/ applying finishes, and polyfilla. Takes some
time to learn. I can be trusted to do it the way it should be done. Of
course it raised the grain, and it has the speckled appearance where it
looks like sand at the bottom of millions of whirlpools. I am not sure how
much MS I would need to effect the advantages, and since it is the inside 5
of drawers I probably won't chance - ok maybe I'll flip it on its side and
try MS. I think I will use three coats of poly. This is the most
protective. Spar, yes not the hardest, allows for movement, stops cracking,
and I have put about 400 ft sq. of it on my picnic table and it gets hard
enough. Not for floors though. Do not use high-gloss to use outdoors. I'll
w/r/t to final finishing, don't know who posted w/ 600 recommendations, but
I'd like to know more. For now, just specifically about this project. I
know I am going to want to do something! I've got 220, 320 400, 600, 1000,
1500, & 2000 SC papers. And 3M rubbing compound fine. These drawers are
white outside including an extremely accurate chamfer on the inside of the
top where the edge meets the inside of the drawer. Looks awesome. You can
only tell there is a lock joint on half of the sides. However, there are
gaps at the bottom to sides - it is NOT air tight. Most of the insides is.
Do you need to wet sand (as opposed to dry sand) if it is after the final
coat? Would you need to do more - like wax. I've got a messy Johnsons
furniture polish wax that is the colour of buffing wax avail at Lee Valley.
must be nearly the same.
Probably too coarse. Remember, there's a difference between leveling and
toothing, and use a semi-rigid block under the paper to level. One of the
_many_ reasons, most of which have been embedded in my sking, that I don't
use flexible stuff like steel wool.
The reason(s) you sand are to level and to provide a mechanical hold for the
succeeding coat. I can't think of any reason why you'd want to sand after
the final coat, if that coat is properly applied, unless you're trying to
cut the gloss. Wax will cut the gloss a bit because of it's polymer size,
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