X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 01 Oct 2006 23:33:50 -0400 Message-ID: X-Original-Return-Path: Received: from elasmtp-junco.atl.sa.earthlink.net ([209.86.89.63] verified) by logan.com (CommuniGate Pro SMTP 5.1c.4) with ESMTP id 1428622 for lml@lancaironline.net; Sun, 01 Oct 2006 11:37:20 -0400 Received-SPF: none receiver=logan.com; client-ip=209.86.89.63; envelope-from=leighton@teleport.com DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=teleport.com; b=pu5vu0Z0KW9L64d/Kc3Fx5//HHhU4MkwEyA/FuyeypvZ4uAgv2TtAtWqNgrXK1M+; h=Received:Message-ID:From:To:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE:X-ELNK-Trace:X-Originating-IP; Received: from [4.242.171.191] (helo=user) by elasmtp-junco.atl.sa.earthlink.net with asmtp (Exim 4.34) id 1GU3Ms-0001L3-6f for lml@lancaironline.net; Sun, 01 Oct 2006 11:36:40 -0400 X-Original-Message-ID: <000601c6e56f$638ca4d0$bfabf204@user> From: "Leighton" X-Original-To: "Lancair Mail list" Subject: Primers X-Original-Date: Sun, 1 Oct 2006 08:36:02 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0003_01C6E534.A0B00C70" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2869 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2962 X-ELNK-Trace: ea0fe3d44b30ba0fc355332e9c4b49d598c48853aa0a5d892f89e20ec70f2096005279d21779e724350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 4.242.171.191 This is a multi-part message in MIME format. ------=_NextPart_000_0003_01C6E534.A0B00C70 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I think I have denuded enough sandpaper over the years to add my two = cents worth to the discussion on priming/prepping composite surfaces for = final paint. First, no matter what primers are eventually used I think = it's extremely important to properly prep the surfaces to be painted. = By the time paint is applied these parts have had plenty of opportunity = to become contaminated with mold release, finger print oils, hydraulic = fluid residue, beer foam, and whatever other aerosols that float around = the shop. I sand the surfaces with 80 grit and then wash them very = thoroughly with prep-sol, acetone, lacquer thinner, and/or whatever good = solvent I have. At the suggestion of the person who was to do the final = painting we started using PPG K-38 high build primer surfacer as the = initial covering. This is applied with a 4" paint roller, unthinned, = and does a great job of filling any pinholes, scratches, bare micro, = etc. It tacks up quick enough that a couple coats can be applied in = quick succession, giving a good build up. This is sandable in an hour = or so. All the sanding at this point is done with 80 grit dry. If you = use a long board on the flat surfaces, like wings and tail, the high and = low spots show up well and will probably level out with a couple = applications. Then, again per the painter, a coat of PPG K-36 primer is = sprayed on. If spraying is impractical this can also be rolled on and = lightly sanded to remove roller marks. I really don't like the idea of flying in primer for many reasons but = it's often the only choice. Primers don't provide a good smooth surface = and tend to act like a sponge to exhaust residue and other contaminants. = A professional painter, if he's good, will sand off most of the = primer/surfacer you've put on and clean everything real good and then = start over in the paint process. If not, it's likely fisheyes and other = bad things will happen. I have used WLS primer and have no doubt that it does produce a great = end result. However, I don't like it's very slow curing time. Like any = epoxy product it feels cured but is not ready to sand for many hours, = preferably overnight. In talking to some experienced body shop experts = they have told me that on bare metal the epoxy primers are definitely = the best choice for their superior adhesion but on composite surfaces = they think it's overkill and just as good a result can be had with the = urethane primer/surfacers. One of these professionals works almost = exclusively with aftermarket fiberglass street rod bodies and I tend to = believe what he says. Recently I built an epoxy/fiberglass replica sports car body from = scratch (if I start another one will someone please shoot me) and it = required a lot more surface finishing that your average Lancair. In = shopping for a more economical primer/surfacer I discovered a product at = my local NAPA (National Airplane Parts Association) store that is about = a third less expensive than the PPG products. It's their house brand = (made by Martin Senour) called Crossfire 2K Fast Filling HB Primer, = number 15222. It's a two part urethane and after using a couple = gallons, so far, on the car body I like it very much. Covers good, = dries quick, and sands well. And it's cheaper. =20 These are just some observations and opinions I have formed in the = process of building five Lancairs and a few other toys and should not be = taken as more than just that; my opinion. The reason we put the word = "experimental" on our planes is so we can do them the way we want, = within reason. I'm sure everyone that has prepped a plane for paint has = his/her own ideas on the best way to do it and whatever works for the = individual is what they should do. The main purpose of the LML, in my = opinion, is to share what has or has not worked and let each builder = wade through the info and reach their own conclusions. Gotta go, I hear the sandpaper calling. Leighton Mangels ------=_NextPart_000_0003_01C6E534.A0B00C70 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
I think I have denuded enough sandpaper over the = years to add=20 my two cents worth to the discussion on priming/prepping composite = surfaces for=20 final paint.  First, no matter what primers are eventually used I = think=20 it's extremely important to properly prep the surfaces to be = painted.  By=20 the time paint is applied these parts have had plenty of opportunity to = become=20 contaminated with mold release, finger print oils, hydraulic fluid = residue, beer=20 foam, and whatever other aerosols that float around the shop.  I = sand the=20 surfaces with 80 grit and then wash them very thoroughly with prep-sol, = acetone,=20 lacquer thinner, and/or whatever good solvent I have.  At the=20 suggestion of the person who was to do the final painting we started = using PPG=20 K-38 high build primer surfacer as the initial covering.  This is = applied=20 with a 4" paint roller, unthinned, and does a great job of filling any = pinholes,=20 scratches, bare micro, etc.  It tacks up quick enough that a couple = coats=20 can be applied in quick succession, giving a good build up.  This = is=20 sandable in an hour or so.  All the sanding at this point is done = with 80=20 grit dry.  If you use a long board on the flat surfaces, like wings = and=20 tail, the high and low spots show up well and will probably level out = with a=20 couple applications.  Then, again per the painter, a coat of PPG = K-36=20 primer is sprayed on.  If spraying is impractical this can also be = rolled=20 on and lightly sanded to remove roller marks.
 
I really don't like the idea of flying in primer for = many=20 reasons but it's often the only choice.  Primers don't provide a = good=20 smooth surface and tend to act like a sponge to exhaust residue and = other=20 contaminants.  A professional painter, if he's good, will sand off = most of=20 the primer/surfacer you've put on and clean everything real good and = then start=20 over in the paint process.  If not, it's likely fisheyes and other = bad=20 things will happen.
 
I have used WLS primer and have no doubt that = it does=20 produce a great end result.  However, I don't like it's very slow = curing=20 time.  Like any epoxy product it feels cured but is not ready to = sand for=20 many hours, preferably overnight.  In talking to some experienced = body shop=20 experts they have told me that on bare metal the epoxy primers are = definitely=20 the best choice for their superior adhesion but on composite surfaces = they think=20 it's overkill and just as good a result can be had with the urethane=20 primer/surfacers.  One of these professionals works almost = exclusively with=20 aftermarket fiberglass street rod bodies and I tend to believe what he=20 says.
 
Recently I built an epoxy/fiberglass replica sports = car body=20 from scratch (if I start another one will someone please shoot me) and = it=20 required a lot more surface finishing that your average Lancair.  = In=20 shopping for a more economical primer/surfacer I discovered a product at = my=20 local NAPA (National Airplane Parts Association) store that is about a = third=20 less expensive than the PPG products.  It's their house brand (made = by=20 Martin Senour) called Crossfire 2K Fast Filling HB Primer, number = 15222. =20 It's a two part urethane and after using a couple gallons, so far, on = the car=20 body I like it very much.  Covers good, dries quick, and sands = well. =20 And it's cheaper. 
 
These are just some observations and opinions I have = formed in=20 the process of building five Lancairs and a few other toys and should = not be=20 taken as more than just that; my opinion.  The reason we put = the word=20 "experimental" on our planes is so we can do them the way we want, = within=20 reason.  I'm sure everyone that has prepped a plane for paint has = his/her=20 own ideas on the best way to do it and whatever works for the individual = is what=20 they should do.  The main purpose of the LML, in my opinion, is to = share=20 what has or has not worked and let each builder wade through the info = and reach=20 their own conclusions.
 
Gotta go, I hear the sandpaper calling.
 
Leighton Mangels
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