wavy grains

[imported_maguro]

I have just finished my hull and am ready to glass over the fir plywood. I filled several checks with epoxy and fairing filler. My question is about the ridges and valleys created by sanding. The softer lighter colored areas in the wood sanded deeper than the darker. Will they stick out like a sore thumb after glassed and coated with three layers of epoxy and a coat of paint? Should I try to fill in these valley's?
thanks for any advice
Chris

[JMAC]

I called a boatbuilding friend of mine with a question along those lines. His wife answered and said he wasn't there and that I should just go ahead and do it the way I thought I should. So, I say to you, look at the ridges, trust your own answer.

[JimD]

On my fir plywood hull I coated the entire hull with epoxy, let it cure, washed to remove any blush, then faired with balloon filler, and sanded. Then put the fiberglass on and lightly sanded with fine grit ie 150-220. That revealed, and maybe even created, a few more little spots that still needed a tad more fairing.

Painting will always show off any unfairness so do that only when you're satisfied with the fairness.

regards, jimd

[jeff pierce]

Yes, the ridges will very likely still show. JimD has the right approach, IMO

-Jeff

[NormMessinger]

I donno, JimD's method might be okay for a boat but I'm leary of anything, such as filler, that forms the bond between the glass and the wood. Better I think, to glass first then fair. Either way, in a year or so you'll catch the light just right across the hull and you'll see print through. Don't mention it, no one else is likely to notice.

Joy to you.

--Norm

[On Vacation]

Depending on the types of boat and size you are building, you can create a lot of work for what you will be gaining to make the end result shine not show it. Building with fir plywood, especially Orange store stuff, you will never have the showroom finish a year from now that you will attempt to have when finishing it new. Cut out and fix cracks with the thickened epoxy and glass over for safety and to minimize any potential delaminations you make have from the lack of bonding of the glass down the road.

Remember to buy the best woods possible because the work is less next time. If this boat is a small runabout, finish and enjoy and start your next one and use the experience from this one to not make the same mistakes on the new ones.

[Jim Budde]

1. Remember, you are building a boat, not a piece of furniture
2. The day before you launch will be the last day your boat will look perfect
3. I'd glass and then fill any obvious low points. A shortcut might help .. mix some pigment with your epoxy ... preferrably the same color as your finish coat. After it sets, a light sanding will show any irregularities. (Just make sure the pigment is compatible with the epoxy you are using)

[Bruce Hooke]

First off, I'm not sure if you were already planning to do this, but if you don't include some 'glass cloth in the epoxy then the plywood will check right through the epoxy, which will not look pretty.

How much the waves in the plywood will show depends in part on what color paint you use. Dark, glossy paint will highlight any waves, whereas lighter, lower gloss paint will hide them. A lot also depends on what sort of look you are going for; or how much of a perfectionist you are! If you add some colorant (available from Gougeon) to the epoxy, you might be able to get some sense of how things will look while you can still easily do some fairing. It basicly comes down to how much work it's worth to you to try to hide the waves. What you have also probably learned in the process is that fir plywood is a pain, and that, if you are going to use fir plywood, sanding should be kept to an absolute minimium, and should be done with a hard backing behind the sandpaper.

I certainly agree that before doing any fairing you should get at least one coat of epoxy on the hull...

[Tom Lathrop]

If you plan to sheath with glass, and you should, the advice to glass first and fair with filler second is the best.

It has not been mentioned, but the real problem is that the surface should have been sanded only enough to clean it before finishing. As you found out, this will always accentuate the wide growth ring pattern in fir where there is a great difference between the hardness of early growth wood and late wood of the annual growth rings. The power sander is the most over used and abused tool in the shop.

[Ian McColgin]

The other cause being the soft pads on power sanders. On curved surfaces, it's really hard to beat a slightly flexable sanding board powered by norweegan steam.

But what's done is done. Most likely the little waveyness won't come up through the glass anyway, but I think I'd put down a layer of epoxy spread with a spatula and sand that by hand with a board just to really look at how much of a problem you have.

G'luck

[JimD]

Originally posted by Ole Scarbutt:
I donno, JimD's method might be okay for a boat but I'm leary of anything, such as filler, that forms the bond between the glass and the wood. Better I think, to glass first then fair. Either way, in a year or so you'll catch the light just right across the hull and you'll see print through. Don't mention it, no one else is likely to notice.

Joy to you.

--NormI know what you mean, Norm but of the two choices 1) Epoxy, then fair, then glass, or 2) Epoxy, then glass then fair, I think the difference amounts to 6 of one, half a dozen of the other.

Should the glass go directly on the wood leaving the fairing compound exposed to the outside? Or should one worry about the very unlikely event that fairing under the glass may come free from the wood? It won't, not without taking the top veneer of wood with it, which won't happen either.

Perhaps the most important thing to keep in mind is not to sand the bare wood to smithereens trying to get the proudness out of the grain. Just sand lightly and get some epoxy and or fiberglass on it, and fair from there.

jimd

[jeff pierce]

Come to think of it, when I had this problem I found that when I applied the first layer of epoxy, the plywood soaked it up pretty good. Once it cured, the resulting epoxy impregnated plywood was more of a uniform hardness across the grain. At that point the high spots could be sanded out, as long as I wasn't too aggressive.

It worked for me.