Hi Craig

 

Don't give up, you are just getting to the fun part!  OK, there aren't a whole lot of fun parts to body work but there are several to keep in mind, first off, assume you will have to do this several times and NEVER, NEVER, NEVER do anything without a board.  For curved areas, a rubber block is good or sometimes I use neoprene or a neoprene sheet bonded to rubber.  The point is there is no one right sanding board, but there are a Hell of a lot of wrong ones and a bare hand or finger is in 99% of all cases the "wrong board". 

As to the part that looks like do-do, yeah, that's normal.  So spot prime it with the HVLP.  It's more work at the front (setting up the gun and cleanup) but the work at the back is a lot less and easier since you don't have bumps to sand at the old dry paint/new wet paint interface like you would get with a roller.  And always use a sanding board of the correct length and stiffness. Make new ones if you have to (about half of mine I made).

 

I'll digress a bit here too and say that pin holes are the work of the Devil and were put here on Earth to make us suffer for our sins.  That comes as no surprise I'm sure to many of you.  So I attack these first BEFORE I start spraying or rolling paint.  I mix up some primer and go over the surfaces with a cheap yellow plastic squeegee forcing the primer into the holes.  So in effect, I use the primer as a very thin putty.  The problem with spraying is that it doesn't go into the holes because of surface tension. So you sand off 99.9999% of the paint in your first shot if that's how you try and get rid of the pinholes.  So my suggestion is go the other way.  Fill the .0001% of the surface before you start the sanding primer part.  You can do the whole plane with a pint of primer.  I am going to try something else the next time I am filling pinholes (I'm doing a carbon cowling on a new airshow stunt biplane with a turbine, thrust/wt is calculated at 1.6:1). OK, that's just gossiping to make you all say "Tell me more", but I do have that project that I will be trying some new techniques on.  I am going to use a rag saturated with primer and wipe the surface down flooding the area.  My plan is to reduce the time and care required in squeegeeing.  I think wiping with a rag may go a lot faster and do a better job. I'll let everyone know how it works once I test it.   If that doesn't do well, I'll try an exorcism to see if purging the demons in the pinholes helps.  And I'll use a sanding board of the correct length and stiffness to help banish those demons!

 

The point is that by filling pin holes first, you don't waste a lot of time sanding unnecessarily.  This means your next coats will be just for fairing and making the plane perfect.  And this is the fun part because once it is all one color and sanded into faired perfection, I get excited. I love to see the change from a perfect shape to a perfect shape with gorgeous gloss colors.  That keeps me going!  But I got there using a sanding board of the correct length and stiffness.

 

 

Next, many people start off WAY too fine on the sand paper.  You kill yourself starting with a grit that is way too fine when you will be priming again anyway.  Any custom laminate job I assume cannot be done for less than 3 coats of primer.  And I have done way too many composite jobs to ever think I can do a decent sanding/fairing job in one coat. Perfection takes several coats, time, patience and long-boards.  But I try to figure out where the highs and lows are and shoot more in the lows to help fill faster.  So go straight to 80 grit until you get to the last coat before gloss.  The sanding will go 10X as fast.  Sanding is non linear.  Fine paper clogs a LOT faster than coarser grit so 80 grit goes many times faster than 120 or 180.  Of course, you can get into the laminate faster too, so always be careful.  A board that is too stiff will not make required curvatures and can cut into the laminate.  So always use a board of the correct length and stiffness, (are you sensing a theme here?)

 

As for paint, I like US Paint's Awlgrip or Sterling.  They can easily cover sanding with 180 grit done from an orbital sander and 220 by hand.  So why go finer?  Test this with your paint but you will get a fairer finish with coarser grit because it cuts the primer better.  There are a lot of other great paints but it could be worth your while to do a little practicing to make sure you don't go finer than you need to.  They flow much better than some of the older formulations did so don't be surprised if you really don't need to go ultra fine.

 

Good building and don't get discouraged!  It will be worth it when you get your first look at those gorgeous Lancair lines in wet looking painted perfection!  And always use a board of the correct length and stiffness!

 

Dan Newland

Craig Berland <cberland@systems3.net> wrote: