Do you prefer to rough sand with a hard or medium pad? Do you prefer an 8" pad for rough sanding or is there something to be gained by going smaller? Also are you fine sanding with a hard or medium pad or is it soft pad only for removing scratch marks? Also are you hand sanding at all? I’ve also been hand sanding using a narrow wooden block with sandpaper wrapped around it after rough sanding with my electric sander as I’m on a quest to get a sanded hot coat as flat as possible. Bad idea? Let me know what works best for you if you don’t mind.
a million different ways to skin a cat…every sander has his own routine. a LOT of it has to do with how the board was lam’ed prepped and hotcoated…
to answer a few of your questions:
8" - only reason to use smaller is to get between glass on fins
hard pad and corser grits for removing material & leveling. soft pads and finer grit for removing scratches. that being said i will start with a hard pad when polishing a gloss.
hand sand only around nose and the sharp edge by the fins. i have a poplar 1x4 block that has a hand sanded radius to fit the fillet on glass ons and a piece of hard foam that i can place on the block then wrap in sand paper that works really well on rails.
sometimes i will hard block sand before a gloss coat
i was a sander in a factory for a while and this is my routine for a sanded finish using power pads and an automotive polishing ‘sponge’ pad:
obviously this can vary greatly depending on the technique and what condition the board is in before you start sanding 
grinder wheel (50 grit) for plugs/boxes
150 on a hard pad on deck. sand lightly.
220 on medium pad on deck. after sanding deck take the tape bead off the rail & straighten sharp tail edge.
320 on soft pad on deck. after sanding deck hit high spots on rail.
take some worn 150 and wrap around block with ‘yoga matt’ foam and tune in sharp tail edge.
320 on sponge pad on deck & rails.
100 on hard pad over fin box/plugs and any high spots from a lousy hotcoat.
150 on hard pad whole bottom. define trailing edge and really flatten the hotcoat in this step.
220 on medium pad whole bottom to clean up scratches and take out any remaining shinies and slight warbles in the hot coat.
320 on soft pad whole bottom to clean up scatches. blend soft rail in this step.
320 on sponge pad whole bottom and bottom rail.
hit any rail imperfections with some 220 or 320
some polish and scotchbrite as a final step helps cover any weave and gives a nice finish! red for matte, grey for shiny (you probably need to go to 400 if you use the grey) i have a scotchbrite glued to an old powerpad - that works great! or you can use a scotchbrite with no polish for more of a matte finish/prep for paint.
hopefully some others will chime in - the threads on sanding & polishing are always great - so much good info from different people who use different techniques.
Thanks Grasshopper. Don’t forget how well the shape was finished as well. Sanding pre shapes with a soft pad (super soft pad?) and electric sander would be an absolute nightmare to flatten at the “end of the line” I reckon. I like your idea of starting(?) with 150 grit on a hard pad for the rough sanding and saving the 100 grit for completely levelling the boxes and crappy spots. Will give that way a whirl on the next board as I think it would work much better than starting with 100 grit for everything.
Hey Grasshopper,
Good tips, thanks for sharing.
Is that for epoxy or poly? I do just about the same as you for epoxy, only I start at 100 with the Hard PowerPad to 150 with Medium to 220 Soft… then 320 wet and so on but stop at 600 (if I even go that far)
Yesterday I sanded a board and tried something new - a quick hand sand with “yoga mat” padded block and 80 grit to knock down the high spots on a crappy hotcoat. No more than a few stokes over each area of the bottom and deck, then proceeded with the normal PowerPad method. Seemed to go well and less work on the 100 grit.
The PowerPads durometers each have a recommended sander RPM to run at but I run all of them at a slow rate to keep from sanding through to the weave - which I used to have a big problem with because I suck at sanding! Getting a lot better with slower speed and more patience.
~Brian
Not much of a flatness difference in using 6 or 8" pads if you’re good at sanding. I use 6" for economic reasons; you can get two disks from a single sheet of paper. Being a good sander has more to do with being a really good glasser. The effort needed to sand hotcoats is proportional to how the lamination was done, final finshing is proportional to how well the glosscoat was applied. If you focus on developing your glassing skills, sanding will become a non-issue. Trust me.
Any tips for getting a glass job flatter?
On laminations, it’s basic squeegee technique. Most people don’t have trouble with the flats, it’s the laps that get sloppy. Be sure that you pull off the resin a few inches beyond the tape line. Freelaps are always messy, it takes a lot of skill to cut and prep cloth to minimize the strings. On hotcoats and glosscoats, the key is resin viscosity. With epoxy, I always heat it up; with poly I’ll add some styrene/SA depending on temperature. I use the cheap 3" brushes (I reuse them) for hotcoats, and a larger Purdy (always soaking) for gloss. Pour two lines lengthwise, distribute it evenly, brush crosswise (from the middle out to each end) rail to rail, then lengthwise tail to nose. Pull off the drips on the lengthwise strokes from the rails. Only pull the brush, none of that shellackin’ movement. Keep taking the excess off the brush with each stroke. If you’ve brushed it correctly, there will be hardly any drips at the tape lines. Really good glassers don’t use any tape on hotcoats because there’s hardly any drips. What’s left is often pulled around the bottomside with a squeegee. Once you get the tapeless technique down, you’ll be sanding even less; and never hitting weave on the rails taking down a tapeline. Just remember, good brush out = no drips.
It’s easier to go a couple of different production glassers and watch. Look at the squeegee pressure/angle and the same with brushing.
All good points from Grasshopper and PeteC…
As a sander I’ve been spoilt in the past by the work of a highly skilled long-time laminator. The difference between that and sanding the work of a sloppy laminator is the difference between routine/predictable results and a mission from hell…
The said-same laminator tells the story of how he developed bad habits he never spotted til the whining sander literally handed him the machine and said- “Do it yourself!”
I’ve witnessed some major barnys between sanders and laminators over this point! Its hugely amusing!
When you do both yourself, you learn really quick! What I tell the occasional fledgling laminator is :- If you are only going to sand it off, don’t put it on! (Usually said pronto after being railroaded into sanding some newbies’ first effort…like, lets grind off those inch-thick rivulets of excess resin edge!)
Two times I’ve stood by watching such a newbie take on his first sand-job, warning the guy to beware of catching his dust-suit in the machine…(g’worn, guess what happens!) Neither of those young fellas progressed to a second board…I guess I’m different…I did the dust-suit trick TWICE!
The difference I find with epoxy sanding is a simple matter of pausing occasionally to blow dust out of the paper grit. Apart from that its a cakewalk…even easier for me as I go to only 150 on my composites when I’m due to do full filler coat spray artwork because paint covers scratches…
Josh