When is fair "fair enough?"

[slowpoke]

Just dropped my keel and bulb 2 feet, knocked out a surprisingly small area of fairing compound on the side. Do I really have to fill in all these little bubble holes?

[slowpoke]

Any suggestions on what's best to use? We're talking pits the size of the head of a pin. Seems like every time I try filling them, the filler just falls out when I'm sanding.

[Tim Ford]

Think golf ball. Those little dimples really do something.

are you saying my boat will rocket off the line for about 150 yards and then swerve dramatically to the right, possibly menacing people in the other fairway???

[jeff.dalsin]

Just remember, TF: Trees are 90% air.

[Chad]

Any suggestions on what's best to use? We're talking pits the size of the head of a pin. Seems like every time I try filling them, the filler just falls out when I'm sanding.

Sounds like a lack of adhesion or contamination, and filler that's too thick. So, wash the foil with a bristle brush and lots of plain water and then wipe with paper towels, blow out the water and dust in all the holes, then wipe with alcohol. Mix your filler a little thinner, like mayonnaise maybe, and consider doing one side of the foil at a time to let gravity keep the filler in the holes.

If the holes are really small, you can probably just ignore them and keep fairing as if they aren't there, then let your first two coats of primer fill them.

For Kevin's slogan thread, "filler converted to dust on the shop floor is fast".

[slowpoke]

Thanks guys, I'll give it another shot...

[jerome]

İ was going to say the same than Chad about the mixture of your fairing. Probably too much fairing and not enough resin.
For fairing İ have developped my technique which is worth what it is:
For the first layers of fairing, İ use a rather thicker mixture. Very important however to wet the surface with resin before spreading the blob. İf you do, it will stick immediatly. İf you dont, you have a chance of "rolling" a blob of fairing around until the surface gets wet and the fairing sticks. This mixture will leave pin holes.
For the last layers, İ use a somehow softer mixture. İt spreads better, a has a more shinny surface than the thick stuff. That layer leaves no pin holes.

By the way, even with the smoother, wetter fairing blob if you wait to long to apply, it will eventually lead to pin holes. So the best is to mix thoroughly to that shinny, soft consistency and apply immediately.

[jeff.dalsin]

The "shiny" finish that Jerome alludes to is also lost if the mixture is "worked" too much. I think that once I was done fairing my bulb I gave it one coat of neat epoxy to fill any pin holes. As Chad mentioned, the first coat of primer should take care of that as well.

[Chad]

Also, it's helpful to do a round of primer once you've done a few rounds of filler and fairing, to better reveal the shape without the visual distortions of the various colors of filler. You need to use really good primer for this, though- something like Interlux's 2-part Epoxy Primekote (wear a respirator!). Then use an appropriate sanding board to fair the primer, circle the low spots, prep the surface and add more filler. Continue with two or three rounds of filler and fairing and then add (hopefully) your final coat or two (wet on wet) of primer. Done well, you should be able to turn the whole surface from shiny to matte by sanding with appropriate sized fairing boards, meaning there are no low spots. Don't sand with your fingers at this stage. Another slogan: "The fairing board doesn't lie". The tools and methods you use will get results that are more fair than your hands can feel or your eyes can see, if you have the patience.

[Kevin]

Another option to Chad's primer idea is pigment in a coat of neat epoxy. You do go sort of "snow blind" when looking at many overlapping layers of fairing compound. It won't be completed opaque but it will be enough to tell the difference when you hit it with a fairing board. Remember to wash before you sand to get the blush off (especially if you use west systems). Don't sand first because you'll just push the blush around (and into the scratches). And if you are using a filler with micro balloons or similar, then you have pin holes as you sand away the top half of any given balloon at the surface.

Patience and persistence equals fair.

[Chad]

I tend to sand epoxy with nothing finer than about 80 grit paper (unless prepping for clearcoats over wood or carbon), and then switch to primer when I want to go finer. Primer goes on a lot thinner than neat epoxy. I like to use tinted epoxy for earlier coats though, mostly as a guide so I don't burn through to the fibers.

Obviously, there's lots of methods and products to use to get a nice result- I certainly haven't tried them all.

[M&S]

My experience with pinholes and their causes; outgassing, overmixing bubbles in in thicker batches , viscosity, and I think the number one is not applying the fairing compound with enough pressure to fill the pinhole and leave a bit of a "proud" bulg which can be sanded flat . The bulb area is not big and attention with a tongue depressor to each pinhole will be the best way. Sort of like hand to hand stuff. do it thoroughly once with pressure and attention to getting everything you can see is the key.
Use a high build primer with tint and you are able to proceed more easily on final final fairing.