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Smoothing plane


Howard

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I seem to have trouble getting epoxied surfaces really smooth prior to varnishing. For paint, one can fair with epoxy thickened with microballoons, etc. and get a decent surface and you cover that up. Still, it's not all that smooth. Any little blip of a brush mark tends to stand up proud.

I sand and sand and sand, and it looks smooth, but when the paint or varnish goes on, the blemishes pop out. Little blips of old brush marks, etc.

Rather than a long sanding board, which for me clogs up in a heartbeat, anyone ever try or consider one of these old wood planes? They would have a long bed like a sanding board, but would cut rather than sand. The blades are heavy....some over 1/4 inch thick. They are cheap and plentifull in antique stores.

BTW....I've also tried scrapers and they help, but again, the subtle ridges and valleys are still left behind.

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I don't think those would work at all well. For one thing the iron would most likely leave little gouges - Epoxy is hard stuff and would dull the iron quickly.

Couple of questions-

what grit are you sanding with and what grit do you stop with?

As to scrapers, the carbide ones do a really good job. BEST idea is to sand the epoxy well then roll on a THIN coat, let that cure, THEN start sanding. I seldom use a brush putting epoxy on by the way.

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On the long board, I start off with about 60 grit....a 9 inch belt sander belt cut to make it an 18 incher, and glued to a 20 inch board. Problem with this is after a few strokes, the paper is clogged and not cutting. I also use some orbital sanders, and they smooth but don't fair. And even though I use a vacuum to collect the dust, the paper clogs on these too.

On large surfaces, I use the short nap (1/8") foam rollers, but those also leave a stipple finish. Certainly not flat. I've tried the West trick of cutting those rollers in half and dragging them over the finish and they leave little streaks that don't sand out as well.

And maybe we are talking degrees of fair? I get a decent finish, but reflected in light, you can see the defects....and most are more related to pockets than to humps. Get after it too hard and you are into the fiberglass cloth. And again, most of the trouble here is varnished surfaces. On those I paint, I fair those by spreading thickened epoxy with a wall board trowel. two or three coats, sanded between them. That fills the humps and valleys and sands fair, and roll or brush on a thin coat over that to seal the sanded balloons. That fairs up ok. And most of this is on flat surfaces with gravity helping. I don't know how a guy would ever get a good clear surface to varnish on a vertical surface. Fixing the runs and sags would take forever.

The idea with the long plane board was to make micro thin shavings to the point where it was just barely cutting. Taking off the high points to where it was shaving all the way across. Some of these old boys have a really heavy blade. 1/4 inch to as much as 5/16ths. I'd dull the corners and set it very shallow. Epoxy is brutal on cutting tools, but I'd keep it honed sharp and a 30 or 35 degree bevel. Maybe even cut the epoxy while its a bit green. At least that was the thought. I got the idea from seeing the tools the fancy furniture jocks use to get really smooth boards. It may be a very dumb idea.

And while we are on the subject, is there a good way to finish epoxy on outside corners like 90 degree joints? Once you tape those and put down one or two fill coats, its no longer smooth....and any type of hard edge sanding always seems to cut into the tape. I've used the soft foam pads, but they don't cut and smooth.

Nothing against hard work, but I'd rather do a better job by learning to work smarter, rather than harder.

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If 60 grit is clogging that quickly it sounds like either the epoxy is still not quite cured or you are experiencing some blush. Since I'm sure you are waiting for a good cure, suggest a wash down with plain water before you start sanding.

Don't know what grit is on my coarse long board- have to look, but I don't think it's as coarse as 60. That's REALLY coarse.

On the kayak boards, to get a mirror finish under varnish they often go to as fine as 400 grit and wet sand with a block prior to the first coat of varnish. They also wet sand between coats of varnish,, using extremely fine grits too. Personally I've always stopped at 320 but I almost always sand with a block. I guess it depends on just how really smooth you want it.

Of course if you wet sand, you do away with the possiblity of blush, cause the water gets rid of it :D

Later edit-

Well that's a surprise!! Just went out and pulled the paper off my long boards and BOTH of them have not 60, but FIFTY grit on them. Both of them have had long use with no real clogging of the grit.

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Ahoy Howard,

Charlie knows as much as anyone about epoxy, but if I may, let me share with you a couple of similar experiences we had and what we did.

Sandpaper Clog

Like Charlie, I think that sounds like a curing problem. You may not be waiting long enough to begin sanding. That happened with me once or twice.

Another possible factor may be in how you are mixing the resin and hardner. Check your ratios carefully. I messed up here once or twice. Another area we can go wrong, is stirring time. Some experts recommend something around two and a half minutes of stirring.

Dips and Other Marks

Once you've solved the problem with clogging, you should be able to sand out the defects. What we did to get a smooth surface was to use Ripstop Nylon. We bought the fabric at a local fabric store. Applied a light coat of epoxy over our surface, and then attached the fabric and used a squeege to level everything out. This approach worked very well for us. Once everything was level, and the epoxy had cured, we sanded to our hearts content.

Sheba1.jpg

Epxoy can be frustrating, but you can eventually get the best of it. Just keep telling the folks here on the board what's happening, and they'll come up with a good solution. You can trust what they say.

______________

Just as a postscript, here are a couple of more photos, more along the lines of a before and after picture. Here's what our cabin looked like after we had filled the screw holes and faired the defects

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been thinking about this during the night. When we are doing table tops on large dining tables we have similar problems. Getting a dead flat surface that is.

Part of this won't apply to epoxy, but here's the procedure used.

First the surface is block sanded, usually with either 80 or 100 grrit, being careful to always sand with the grain. Then we decide how the stain is to look. If we want a darker look we stain over the 80 or 100 grit sanding, then start the lacquering. If we want the stain to show lighter, we sand to 150, 180 or even 220 before staining. Same stain by the way.

Once the firstcouple coats of lacquer are on, we block sand at 150 and shoot another coat.

Block sand at 180 and shoot again

Blocksand at 220 and shoot again

Blocksand at 320 and shoot again

Repeat the 320 until the surface is what we want then rub out the final coat.

So in doing the epoxy, do the long boarding to level the surface. There's gonna be some low spots. Roll on a very thin coat of epoxy and long board again. and again, and again until the surface comes up flat.

The roll on a thin coat and block sand with 100, then again with 150 or 180, then the 220, then the 320, with a very thin epoxy coat between each. And I mean as thin as you can possibly roll on. Yes, it will stipple but each coat will get smoother and flatter.

Finish by wet sanding, then start your varnish, sanding between each coat.

Finish up by wet sanding the last few coats.

NEVER sand it without a block under the paper and DON"T skip steps in the grits. You CAN'T go from 80 to 220 and get a good surface.

Lots of work, but if you are after a dead mirror finish, that repetitive filling and sanding is the only way.

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Ahoy Howard,

This morning as I read your posting again, I noticed a reference to varnish. Apparently, you want to varnish some of your surfaces and paint others. Here are a couple of photos of what we did.

Our stem is not fiberglassed, but we did encapsulate the wood in epoxy, and then applied a single coat of varnish for temporary protection. (We'll apply multiple coats later.)

pnt10.jpg

Our finish turned out glass smooth. We used a roller to apply the epoxy in very thin coats, sanded between coats, and on the final coat, we did something different. On the final coat, we used a rubber squeege, the ones you use to clean a window. We dipped the squeege into a solvent and lightly smoothed our surface. Here is a close-up of the results.

pnt14.jpg

Yes, we lightly sanded as well, stopping I believe with 320 grit. The finish turned out glass smooth and retained the beauty of the wood.

Howard, one word of caution here. On the stem we tried using Ripstock Nylon as well, but that approach did not work out for us. Unlike the hull, the stem simply has too many planes for the fabric to mold itself to the shape of the substrate. The approach with the rubber squeege and solvent, however, worked quite well.

We followed a similar approach with our transom, but there we fiberglassed the surface. I think we used a 3 ounce cloth, but I'm not sure. Eventually, the weave disappeared. I must tell you, however, that on the transom we have some heat blisters that later appeared, so we still have a little work to do there.

Good luck on your boatbuilding, Howard. You'll get this epoxy application down and become familar with the attending characteristics. You may have a mishap or two on the way, but your boat will turn out fine.

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Too late for this boat. It's ready to be painted. :wink:

But it could still use some improvement on the inside and outside corners. some of those are in really tight places and almost impossible to get any type of tool into. A glob of fully cured, thickened epoxy is tough to fair out when you can't get at it. Try as I did to keep those under control, some sneeked in.

I've got a small rounded carbide scraper I'm using. It works, but not well. Have also tried a Dremel sanding drum (1/2 inch) and it also works, but one has to really be careful or you can gouge your fillet in a heartbeat.

Found a few air pockets under the tape after the seams were sanded down. Never noticed them when laying down the tape and I thought I had done a perfect job with my fillets and laying down the tape, but the pockets proved different. To get those fair, I opened them up and filled the holes with a combination of small fingernailed sized pieces of FG tape fitted into the pocket, covered with thickened epoxy and that with masking tape. A version of using release film. Those came out well and confined the epoxy and further sanding to a small area surrounding the repair. Small card type cabinet scrapers do a good job of cutting any bumps back to fair. Wide masking tape might be just the thing for fairing those outside corners.

Release film is the only way I can think of to get a vertical surface faired well enough to varnish. It seems like the varnish can be brushed or sprayed onto vertical surfaces without running, but epoxy is hard to get on in thin enough coats that set up before it wants to sag and run.

BTW, I used butt joints on my plywood panels and try as I might, the heavy plastic I used between the plywood and clamping boards puckered, leaving a high spot of rippled, thickened (glue thick) epoxy to sand down. That took just about forever! I had hoped it would work like release paper, but such was not the case.

Last, but not least, comes the System 3 fairing system, where they suggest that once the large area is ready to be faired, make a mix of epoxy thickened with the easily sanded micro balloons, and lay that on with a knotched trowel, like the glue used for ceramic tiles. That way, when you are ready to fair, you only have to knock down the tops of the ridges left by the trowel. when faired, come back and roll your sealing coat of epoxy on over that and it self fairs very easy. Again, would work for a large, flat surface you wanted to paint, but not at all for a vertical surface to be varnished.

With that, sounds like you use the very thinest coats you can and sand, sand, sand, or be content with the 20 foot test. I like doing inaccessible lockers best. For those, you can use the "won't be noticed from 50 feet by a man galloping by on a horse" test. :lol:

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One other thing. When fairing a flat surface, even with a long board, you will get some dips and low spots that are below the surface level, so they don't get sanded. Since they don't get sanded, they also stay slick. Do you go in and scuff those by hand? Otherwise, later coats won't stick....they fisheye.

Unless you stay with the long board until it's completely flat. On some surfaces, that would mean taking off the entire coat you just put on.

Also, I had a couple pieces that I used the long board on to fair BEFORE I epoxied anything. 60 grit leaves some ugly, ugly scratches in bare okume plywood.

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Yes on the scuff by hand.

Also- on interior fillets. You can get a very smooth slick surface on those - while wearing your rubber gloves ( or whatever kind) and while the resin is still in a soft state, dip your finger into some alcohol, either rubbing or denatured, and wipe the fillet. Keep wetting and wiping and you can get a glass smooth surface that needs NO sanding at all, other than a fine grit for surface tooth.

I commonly do this on fillets that don't get glassed over, such as hanging knees up under the deck edges, etc.

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BTW....I've also tried scrapers and they help, but again, the subtle ridges and valleys are still left behind.

IMHO you just need to take it down a bit further. Or, lay another coat of epoxy and scrape again. A sharp scraper will make all of the difference. ;) Then follow up with 220 or finer.

That's all I did here. ;)

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There are a couple of approaches you can take to get smooth surfaces. One is to apply enough material (epoxy, varnish, paint, etc.) to fill the low spots to a height that will be above the leveled surface and then sand away most of this. The other is to apply enough material to perform it's duties as a coating, then fill the low spots with enough material to get above the leveled surface.

I use the second approach, preferring to not sand away perfectly good material unless I have to. After the base coats are down and well cured, the first swipes with a long board or scraper will reveal the low spots. Level up the majority of the surface, with low spots clearly visible. Scuff up the low spots and add more material to these areas only. When this is cured, knock them flat. Keep filling these low spots until you are up to the same level as the surrounding areas, then start blocking and fine tuning the surface until she's as smooth as you want.

You can also "flood coat" the area with a lot of material, which works very well on dead flat surfaces, that have been carefully leveled and had a dam of tape wrapped around it's perimeter, before flooding with epoxy. This is how "table top" epoxies are applied. There aren't many areas on a boat that can receive this treatment, but it works well on flat surfaces, like counter tops, thwarts, tables, etc. You have to work in a bug/dust free environment, for a good finish with this technique, or every bug and dust nugget within the room, will find it necessary to check out you work, up close and personal.

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