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fog/wet coat technique on wings

Posted: Wednesday, December 5, 2012 8:46 PM Quote
Hi Jason
Need some further clarification on the fog/wet coat technique for a set of Vagabond wings.

Do you recommend fogging the whole wing, then going back around for the wet coat? or do you do a section (or maybe a whole side of the wing) fog then wet & move on? Worried about the fog coat drying before I get back to it with the wet coat.

Also, these wings will be all one color (white)... any tips on how not to get a dry overspray look at the leading edge? The wing has a pretty good chord length, so with the wing fixtured vertically in the painting fixture (LE or TE up) it's a bit of a reach and definetly hard to get a really good "eye" at 100% of the wing while painting.

thanks!
Posted: Thursday, December 6, 2012 11:47 PM Quote
There is no tack time issues when spraying the fog coat. You can move all over the place with little regard for technique or good gun control so long as you NEVER let it get shiny wet. If you keep the gun held back far enough that you maintain a fairly dry 1000 grit sand paper type atomization and surface texture there is no need to worry about time. Just make sure that the entire surface you are painting has even color saturation before you move onto the wet coat. You can take 10 min, 15 min, 20 min to spray the fog coat. You can go back to areas you may have missed and spray a little more here or there to bring up the color saturation.

When you get ready to spray the wet coat make sure the surface is still tacky. If you lost the tack then hit it quickly with a fog coat. No need to build color.... all you need is a tacky surface to hold the wet coat. If it's super dry and hot and you move v e r y slow you might loose your tack but it's not a big deal. Just fog out about half the surface and come back to the beginning and start laying down the wet coat. When you get to where the fog coat ended just fog the rest of the surface. Think of it as 2 steps forward 1 step backwards as you go.

If you have a rotator and not a fixed position type painting stand then I highly recommend you spray out the full perimeter first and paint the LE back to the front spar on both sides. Then quickly flip the wing vertical and start spraying from end to end moving up and down with one continuous movement.

If it's fixed in the vertical then you need to wet out the LE first. Stand on a step stool to make sure you get a good paint job on the LE. Again try to paint all the way back to the front spar. Then come right back and start your vertical wet coat moving down the wing. If you put a wet edge on a wet edge you don't have the dry over spray look. If the LE has dried and your gun technique is such that you end up dusting the dry LE paint with over spray then you're going to have that dry look when the paint dries. You have about 25-30 min at 70deg F to come back and wet out the rest of the wing after you spray the wet coat on the LE.

It's all about planning, gun control, having a helper to move a step stool and control you air hose, and thinking ahead of the paint gun knowing where the overspray is going to land. Make a few dry runs before you mix the paint and do it for real.

Always paint moving towards the exhaust fan so that you don't suck over spray on to dry paint.

And I recommend painting the aileron hinges first before you even get started on the rest of the wing. Turn you gun way down to make it like an air brush and fog the color into the "U" channel so that you don't get a run. Just keep the air going and fan the paint to help it dry. Figure about 1-3 quick spritz's of paint for every 100 passes of air. Keep going till it just hits the wet look and stop. Let the hinges dry for about 30 min before you start spraying out the rest of the wing.

Jason