I repeated what I’ve seen. Went up the scale in grit numbers til 400, used softer orbital pads as I went up, never held the sander in one spot, etc. I still end up with some scratches in my sand finish, I assume from gunk built up on different spots on the sand paper.
Am I supposed to replace the sand paper for the deck and the bottom? It just seems like a waste of sand paper, but I’ll do it if the tribal elders tell me to.
In the big picture, extra sandpaper is a small price to pay, for superior results. Beware of pursuing false economies.
Some professional sanders use two sheets per side per grit. One sheet of quality sandpaper like Indasa wil do what three sheets of 3M or Norton will do. So if you are using a paper of that quality, there is always a tendency to try to go as far as you can on one sheet. My question is; What are you sanding?? A hot coat/filler coat or are you sanding Your gloss with Wet&Dry? If you are sanding a hotcoat you shouldn’t even have to go to anything more than 220. Most of the time you can stop at 180 or lesser grit. If you are doing a Gloss Wet&dry; maybe you should Wet sand with water. Less possibility of gunk building up. If you are sanding the Gloss, you might want to go to 600 or even 1000. Depending on what keeps coming up scratch wise. No matter what, if you are dry sanding, stop and blow dust etc off your sandpaper and the board from time to time. Use a Medium or hard pad on the flats. A hard flat surface requires a hard pad. The only reason a soft pad is used is to conform to curved surfaces like rails. Lesser experienced people should sand rails and tails by hand. As I stated; I am confused by what you are attempting to sand. Hotcoat or Gloss?
Sanding is pretty much 2 stages - flattening the surface by removing material with low grits (80-120), then removing the scratch marks with progressive grits (150 to 180 to 220…)
You may have missed a grit level in there to remove the previous scratches or cut some deep scrathes with the low grits that you just can’t remove without starting the whole sanding process over. Keep the sander flat to prevent gouging in.
Typically you’ll use 1 piece of sandpaper on the deck and one on the bottom for each grit. Higher quality sandpapers will not clog as quickly. Running a clogged sanding disc will certainly cause scrathes and swirls…
Good advice from Greenlight. But the other question I forgot to ask is; Are you sanding Poly or Epoxy. There is a difference in the way each is approached.
epoxy fill coat…Greenlight’s epoxy actually haha
Do as Greenlight says. You may be better off hand sanding. Once you have broke the surface and created a little dust, you can hand sand. Sometimes it’s easier to see where the scratches are during the process that way. Use a block on the flats and folded sandpaper on the rails. You might also consider using Wet&Dry. The water helps avoid scratching. After all that if you still have scratches; Hit it with rubbing compound. Be sure you clean off really well all rubbing compound. Then you can hit with a finish coat or just Polish what you have.
What grit are you starting with? If your starting grit is too course you will make deep scratches that are hard to get out.
Separately when glassing a board I work by the advice my father gave me for taping and spackling sheetrock. The cleaner your work the less sanding you have to do.
That’s for sure.
I’m starting with 100 grit. I do do the nose, tail, and rail by hand. I’ve been using the same paper on both sides for every grit. The scratches are deep. I really now believe it’s epoxy build up on the paper so I will try a fresh sheet per surface. Maybe steel brush the grit on occasion. If that does not work I will look into the indasa paper.
Epoxy buildup plus wee bits of sanded epoxy which are at least as hard as the epoxy you’re sanding that have embedded themselves in said epoxy buildup.
A few things-
Technique: use very little pressure on the sandpaper. Higher pressure .not only fuc#s the paper up more quickly, it makes heat and friction, which softens up the resin and lets it gum up the paper faster. It doesn’t sand the resin any faster. If your hand gets warm when sanding, that’s telling you something.
This is one of the nice things about wet/dry paper used wet, it not only floats particles away, it cools the surface you’re working on.
By the way, if you’re gumming up the paper when its used wet, something is wrong and your resin hasn’t hardened completely or again you’re sanding way too hard with not enough water or both.
Taking a wire brush to sandpaper- really? Several things about that will give you trouble
First off, in use steel wire brushes and steel wool.have tiny bits break off. They stay on the surface and in time, in a salt water environment, they rust, even stainless. You get these nifty little brown freckles. If you have some in your paper, and you will, some will find its way to the board.
Next, if the paper is gummed up, chances are that enough effort to de-gum it with a wire brush will tear it… And it will almost certainly remove enough of the abrasive particles from the paper as to make it pretty much useless. Oh, and if the paper is that gummed up, it’s toast. Pitch it.
Now, you have been at this a while, Your time is worth something. Even your time fruitlessly wire brushing sandpaper. Compare that to the really minimal cost of a few lousy sheets of sandpaper. Let alone the time pissed away in having to redo and redo and redo. Change the fuc#ing paper already. Check it regularly and often, if it’s getting clogged, slap it against something a couple of times and the dust should fall out. If it doesn’t, change paper, right now. If you’re out of paper, have a beer and take the night off, get more in the morning.
Indasa paper is lovely stuff- used right, carefully, it lasts a long time. Used wrong, it’ll gum up too. For the moment, save your money and just change your technique…and change the damn paper.
hope that’s of use
doc…
‘‘Doc, you need to take a deep breath, and tell us what you really think.’’ (points given)
I hate sanding epoxy. When you get into the finer papers you get the little beads the instant the work heats up.
Every shop should have one of these gum rubber abrasive cleaning sticks. Extends the life of abrasives and helps to eliminate sanding swirls. Lasts for years. You can use the sole of an old skool wallabee shoe too.
(chuckling) - ah, once opon a time, I started out doing woodwork, Boat carpentry/boatbuilding as my father’s apprentice, wood commercial fishing boats.
( a medium-sized book omitted, though one of these days)
One task that I wound up with fairly often was nipping the ends of bolts off with a sawzall. We used a lot of galvanized carriage bolts for all kinds of things, often drawing things together with 'em so that the ends of said bolts stuck out a ways and would give the guy running the boat a nasty dent if he hit it. So, nip 'em off.
Now, The Old Man was funny about some things. I was beng paid a decent hourly rate, fine, tools were good and he didn’t begrudge me the time to maintain them. If there was a better, faster tool out there for a job he’d buy it. But for some reason he was awfully tight about the sawzall blades. I would catch helf if I replaced one.
So, pissing away my decent hourly rate, I would be trying to cut steel bolts with blades that had virtually no teeth left. And that wasn’t just on the easy part of the blade to get on the bolt, but down to the shank and up to the tip, getting cute with it and any teeth that were left. When I was finally allowed to replace one it wasn’t good for anything beyond butter and that’s just because it was that hot from pure friction. Took a helluva lot more time than it should have and also resulted in a less than joyful apprentice.
After that, I’ve been real big on not wasting time when it’s just a matter of replacing a cheap blade or a cheap piece of sandpaper or a grinding disc, etc. As Bill said, there’s such a thing as false economies, spending dollars and time to save a very few pennies.And on a job if I see somebody struggling with a dull tool, and that includes sandpaper , change the damn paper would be the mildest way I would put it.
Funny, a job I was on afterwards ( for somebody else) , before I came in they had a bolt cutting job. It looked like the Sawzall Blade Fairy had been there, sprinkling busted blades all over the place.
What The Old Man would have thought of that…
doc…
I heard someone call it “Holding up a dollar to save a dime”.
Me too. I hate sand fine at all LOL. For sanding, epoxy must be fully cured=hard and chemically free so you reduce clogging and allergic risks. Depend how it cure but some epoxy brand need first a wash with scourer and water before sanding. Then sand with low pressure and speed with not to coarse grit, best tool is random orbital sander with vaccum cleaner: paper move fast, dust are vacuum out and surface is cooling by air flow. That way with good sander you can go up to 1000 and more grit.
