Fred,
No I did not use the PrepWipe because I found I could do without it, that a
final
finish sanding worked equally well, maybe better. To emphasize, as it would
seem intuitively obvious, the surface you end up painting must be free of
contamination.
Some additional thoughts. Obviously there are several ways to skin this cat,
many
will work and some will prove not compatible. Some basics that spread across
all the different methods or systems. Be very careful and knowing if you
want to mix or apply different products and particularly, if you want to apply
one product on part of the plane and some other product on another part. When
you paint over the intersection between multiple products the paint will flow
at least a little differently at this junction and show in the final product.
So it is fair to say that your undercoat primer, whether using SmoothPrime
or something else, it would be safest to have that product consistent and
covering
the whole part being painted. This means that its not favorable to be painting
over a mixture of areas of primer, some areas of raw fiberglass layup and
some areas of another filler. When you have your plane all primed and sanded,
looking rather good, then you paint it and the finished glossy shinny paint
now reveals many imperfections you couldn't see on the sanded or primed under
surface. There are many areas where the sub surface has differences, seams,
joints, and non uniform layup thickness that will now be evident with the nice
glossy paint finish. A common place to see this is where a substructure member
is, like ribs, or the fuselage top to bottom seams, etc.
With the SmoothPrime you will likely sand off 50% or even 75% of an applied
sandable
primer in getting it right, that is the reason for the multiple gallons
of SmoothPrime I suggest you will need. Make very sure you use a "long board"
and sand with long broad strokes. Force yourself to use as little short and
localized sanding strokes as you can. Yes there are some complex curve area you
will have to deal with where long sanding strokes won't work.
Bill
-----Original Message-----
>From: Fred Klein <fklein@orcasonline.com>
>Sent: Feb 21, 2012 7:42 AM
>To: europa-list@matronics.com
>Subject: Re: Europa-List: Smooth Prime
>
>
>On Feb 20, 2012, at 10:21 PM, William McClellan wrote:
>
>> Probably the best answer is, "it depends". Any of your pre-molded
>> parts that have the green/tan factory gelcoat also has some amount
>> of mold release that has to be sanded off so it is safe to say you
>> should sand the whole plane surface and apply your primer. It might
>> be a little picky but the gelcoat provides not structural benefit
>> but does add weight. It goes without saying, you can sand the
>> gelcoat but not any of the thin layer of glass layup. What ever
>> filler you used first, maybe Superfil, is the rough fill, likely
>> with many pin holes.
>
>Bill...thanks for your detailed response.
>
>I agree w/ you about removing most of the gelcoat...carefully...and
>yes, I used Superfil, and yes, I have my share of pin holes. John
>Lawton is a fan of "3M flowable finishing putty" for taking care of
>pinholes. BTW, did you try any of the "Prep Wipe" rather than Acetone
>to clean surfaces prior to applying the Smooth Prime?
>
>Fred
>
>
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