Rascal Progress pics: Bottom painting Experience

[Speedboy]

Here are the before and after photo's of the bottom of the Ken Bassett designed 15' Rascal runabout. The bottom was primed with Epifanes 2 part Epoxy primer (white) and then covered with 1 coat of Epifanes 2 part Polyurethane (dark green). This will be a trailered boat.

http://www.imagestation.com/picture/sraid182/p70f320ae9ace1dd8430327b3ebbdf0f5/f2c1c4f7.jpg

http://www.imagestation.com/picture/sraid182/pea9c8bd8c0c3f6010e82607b4106203b/f2c1c4f2.jpg

http://www.imagestation.com/picture/sraid182/p6c63e61698a3a34b8ec680e84cb821f4/f2c1c4f0.jpg

Here are the after pictures:

http://www.imagestation.com/picture/sraid182/pc11ca98edfadb83c14910299776a2448/f2c1c500.jpg

http://www.imagestation.com/picture/sraid182/pc6f28a30b268d468c1acb75700cbcc99/f2c1c4fa.jpg

I started to apply the final coat of 2 part poly using a foam roller (4" wide) but so little paint was being applied it was not covering the white primer. But I noticed when I applied the paint with a Jen 3" foam brush, it covered perfectly and the brush mark disappeared completely. I painted the whole bottom and it looked really good (not a single brush mark). But when I returned an hour later to remove the 3M Fine Line tape, I found that in many places, the paint had sagged, especially on the side where I was probably adding too much thinner. I realize now that I applied too much paint and added too much thinner. I am deciding now whether to sand it all down again and try one more time. Anyway, here are some things I learned from this attempt, many of which were listed in the roll and tip thread:
1) Apply a thin layer of paint.
2) Change out your foam tipping brush frequently when using 2 part poly. The foam tends to get very floppy after a short period of time and the foam works much better when firm.
3) When masking unfinished mahogany with Fine Line tape, the polyurethane will wick under the tape due to the open grain of the mahogany and you won't get a clean edge.
4) If you wear a Tyvek suit and it's hot, tuck the sleeves into your gloves or you could drip perspiration onto the painted surface.
5) I put the left over paint in the freezer after finishing, and I have used it for the last two days. It appears to be fine. I am applying it to some sample boards each day to see exactly how long you can keep the stuff before it is unusable. Some of this may be common knowledge, but it's all new to me!

Speedboy

[Steve Lansdowne]

Nice job. I gather you're practicing for doing the topsides. The fish will apprecciate your bottom results.

[ 08-18-2005, 09:47 PM: Message edited by: Steve Lansdowne ]

[Speedboy]

I plan to finish the rest of the boat by staining with Minwax Mahogany 605 Gel stain and then 8 coats of Interlux Schooner. I guess it was better to make mistakes on the bottom than on the topsides. I hope this Schooner varnish goes on smoother than the bottom paint.

Speedboy

[Bob Cleek]

Thanks for confirming what I've been saying all along about "roll and tip!" LOL You seem to have identified the problems correctly. Unfortunately, you are about to discover one of the problems with the new epoxy "super" paints... they don't sand worth a damn. Still, if you want it right, you'll need to let those curtains dry and sand it out and do it over again.

There are a couple of issues you missed, however. You are right about the Jen foam brushes losing their "snap" after a while. This occurs much more frequently with "hot" solvent paints like two part epoxies. The solvents degrade the foam. In fact, I've watched people try to apply CPES with foam brushes and the foam just disintegrates! You seem to have that in hand, though.

A similar thing is happening with your fine line tape. Fine line tape isn't intended for use with "hot" solvents. It works fine if spraying, though. The problem is that the solvent dissolves the adhesive in the tape and the paint runs under the tape line. If you are using any sort of epoxy, paint or otherwise, you have to use 3M's puke green (I guess some would call it "lime") "lacquer proof" masking tape. The adhesive formulation in this (somewhat more expensive) masking tape will not dissolve when in contact with the solvents in epoxy or lacquer. Unfortunately, you will really have to press down on the tape line to make sure it is tight because you won't get the "perfect" fine line you do out of "fine line" tape. Expect a line that is somewhere between fine line and 3M blue, well pressed down.

[JimD]

Unfortunately, you are about to discover one of the problems with the new epoxy "super" paints... they don't sand worth a damn. I haven't used an epoxy paint so I have no reason to doubt this but the original post says the primer was epoxy but the green paint is an LPU. The 2 part lpu I've used sands quite nicely. On another note I read in a Classic Boat article that the lpu's are great for plywood and strip planked boats but not so good on traditional plank as the paint lacks the flexibility to move with the planks.

[Carl Stone]

Sorry to sound like a dummey, but did you say you left the paint in the freezer?

[JimD]

Originally posted by Carl Stone:
Sorry to sound like a dummey, but did you say you left the paint in the freezer?Yup, that sounds like what he said! Me thinks he meant he had some mixed paint left over that kept it as cold as possible to keep it from curing.

[Speedboy]

Yes, I did take the leftover paint and put it in the freezer, assuming I would slow down the cure time (for experiment only). I am surprised that two days later it is still liquid. I am using it each day on some sample boards to see how long it remains workable. I thought it might last a day maximium. Anyway, as far as trying other crazy stuff, has anyone ever wet sanded using a palm sander with 220 grit? I would be sure to use a GFCI outlet and I would limit the water used by spraying the water on with a spray bottle as I go, so the chances of soaking any of the electrical components would be extremely low. If this polyurethane is hard, this might be a way to speed up the sanding process. One other thing I did notice during the finishing process. When the two part epoxy primer cured in the bottom of the pail (about 1" thick), I removed it and it was like a rubber disc, very flexible and rubbery.

Speedboy

[Todd Bradshaw]

Bob, that doesn't comfirm a damned thing about roll and tip and you know it. It does confirm that if you put too much paint on in any manner it will sag, but the rolling and tipping had nothing to do with it. People just need to get used to the fact that a paint job doesn't look finished after one coat and to learn to avoid piling up a whole bunch of first coat so that they can't see any primer showing through.

If this boat is built using epoxy (which I can't remember) with large amounts of exposed resin (like coated panels, which I don't know) do some compatability testing with Schooner varnish on epoxy-coated scrap before varnishing the hull. There have been some issues in the past 20 years or so with Schooner not drying properly over some epoxy resins.

[Speedboy]

Todd, the bottom of the boat where the epoxy primer and green polyurethane was put down was West Systems epoxy coated plywood. The rest of the boat is 1/4" thick mahogany. The Schooner varnish will only be applied over the stained mahogany, not over any epoxy.
As for the issue with the paint sagging, I am sure I put down way too much paint for the first coat, but I never really did any of the rolling part of roll and tip, I just put it on with a foam brush. It was more like flow coating. Note the there isn't a brush mark anywhere and the finish is smooth as glass (with lots of sags). In fact the pad keel is pretty much perfect, because the surface was flat. I tried to cover the white primer with one shot, because I had just mixed a $50 quart of two part poly that was in cure mode and wanted to get my money's worth. That was the mistake. I should have split the batch and done two coats.

Speedboy

[Dale R. Hamilton]

Speedboy- 220 grit, no matter how you move it around is too course at this stage UNLESS you plan to follow up with maybe 320 and then 400. Wetting the surface is a lubricant- You pretty much need to block this out by hand with a wooden block. Another thing that will help runs and sags- the automotive paint shops sell a little aluminum block with a series of very sharp chevrons designed to cut down heaped paint. These work very well and all you have to do is touch up with 400 grit. I guess there's another way to attack- Talk a DA with 80 grit and cut it back to primer, then work you way back up to 400.

From your pictures posted- I can't see why you wouldn't spray this job. You are already in some kind of a tent- maybe drape those cabinets. If you don't have an air compressor- these as well as the gun can be rented. After a couple learning trys, you should be able to tackle it.

[Speedboy]

Dale, You may be right about the 220, but I would follow it with 320g and final sand with 400g prior to reapplying the paint. The main reason I didn't spray is that I heard you could get a spray-like finish with roll and tip (and I now know it is possible), and I would have to go out and buy the spray thinner after I already bought the brush thinner. I would also have to borrow a spray gun and compressor. I also figured this would be good practice for when I got to the really important sides of the boat, the deck and topside. I am also leary about getting two part poly everywhere, especially in my lungs, since I only have one of those $30 cartridge respirators. I really don't mind the rolling and brushing, and I think with a little practice I should be able to get satisfactory results.

Speedboy

[Dale R. Hamilton]

Ok understood. More questions. Say you planked this with 1/4" mahogany. Where did you get it, how wide are the "planks", how long are they, assume they are butt jointed, did you have to spiel the planks over each other or just stack them edge to edge and cut off whats left over?
Need these answers because its my next job.

[Speedboy]

Dale, I had my local lumber supplier, Harris Woodworking resaw 4/4 Pattern Grade Honduran Mahogany and then plane both halves down to 1/4". The designer of the boat recommended putting each plank on as one 16' piece, or to put one butt in each plank, with each butt staggered 2' from the previous. I used 12' lengths and the boards were 10" wide. It was tough to find 16' lengths at my location. Resawing these planks requires a pretty big band saw with a good fence, that's why I let the lumber yard do it. Because I used 12' lengths, I did have a butt joint in each plank. After I lined off the boat and put pencil lines where each plank edge would lie, I then individually spiled each plank to the previous. There are several ways to do it, but here is what I did. I took a piece of stiff batten that was narrower than the plank to be created. I temporarily tacked it to the boat in between the two plank edge lines with 18 gauge brads. I marked on the batten the locations of each boat frame (station lines)for reference points(the station locations were vertical pencil lines on the boat) I then made some cardboard pieces and taped them to the batten every couple feet. I cut the top and bottom of each cardboard piece so the top and bottom edge lined up with the plank lines. Where a butt joint would occur, I cut a piece of cardboard to line up with that edge of the butt. I then removed the batten from the boat with the cardboard pieces attached and layed it on top of a piece of the plank stock. I marked all the station lines (frame locations) on the plank stock and transferred the top and bottom edge of each cardboard piece to the stock. I then took a flexible batten and temporarily positioned it along the transferred lines at the bottom of the plank stock and drew the smooth curve created by the edge of the flexible batten. I then used a jigsaw to cut this curve. You then take this rough cut plank edge and temporarily tack it on the boat above the previous layed plank (using the station lines for reference), but space the plank about an 1/8" above the previous plank edge. Next you take a laminate trimmer with an edge guide (the edge guide rides along the top edge of the previous plank in the 1/8" space) that follows along the contour of the top of the plank edge already installed, and run the laminate trimmer down the length of the plank to cut the contour into the temporary installed plank you are working on. Trimmer has a 1/4" double flute carbide bit with 1/4" exposed. When this is done, you should be able to drop the plank down onto the edge of the plank below, and you should have a perfect fit! That should give you a pretty good feed as to what is involved in spiling this way. Some people use the plank they just created as a spiling batten for the equivalent plank on the other side of the boat. Again, there are several ways to transfer the pattern. The trick to this method is the use of the laminate trimmer with the custom edge guide that rides the edge below, creating the exact contour on the edge of the plank you are creating. Hope this helps!

Speedboy