View Full Version : Pin holes (again)
After removing all the gelcoat, a friend recommended applying a very thin cloth known as Vail to fill most pinholes. We brushed on epoxy and rolled on the Vail, followed with thin peal-ply, then squeegee'd it out with excess resin toward the trailing edges of the wing. Not sure it worked all that well and took two of us 4 hours + $400 bucks for Vail, resin and peal-ply. In some areas (near spoilers), we trapped some resin between the Vail and peal-ply which was full of pin holes!
I think the concept is good, but next time I believe I'll skip the Vail and just brush on epoxy and cover it with peal-ply. The resin has got to fill most pin holes and the peal-ply will leave the surface ready to prime.
Would like to know what others are doing?
JJ
On Tuesday, April 4, 2017 at 10:18:43 AM UTC-4, wrote:
> After removing all the gelcoat, a friend recommended applying a very thin cloth known as Vail to fill most pinholes. We brushed on epoxy and rolled on the Vail, followed with thin peal-ply, then squeegee'd it out with excess resin toward the trailing edges of the wing. Not sure it worked all that well and took two of us 4 hours + $400 bucks for Vail, resin and peal-ply. In some areas (near spoilers), we trapped some resin between the Vail and peal-ply which was full of pin holes!
> I think the concept is good, but next time I believe I'll skip the Vail and just brush on epoxy and cover it with peal-ply. The resin has got to fill most pin holes and the peal-ply will leave the surface ready to prime.
> Would like to know what others are doing?
> JJ
If surface does not need any replacement of cloth for structural reasons, I have found the following to work best for me.
1)Blow as much dust off the surface and out of defects as possible.
2) Apply PCL Polyprimer using a 4 inch foam roller using a good bit of pressure on the roller. The first coat is not all that thick and the objective is to work the filler into the pinholes. I use 907 white for these coats.When it has tacked off I roll a second coat which covers and lets me see the defects that are not filled.
3) Spot in all the defects I can see, then spray one coat of 901 gray.
4) Sand and continue.
This usually gets 90-95% of the pinholes for me.
Good Luck
UH
Go with Hanks advice. He guided me in the refinish of CF and it turned out great. I was constantly advised by spectators as to how I "should do it". One guy grabbed a gear foot and promptly sanded through to the foam core. From then on I didn't mind being rude to the next neighbor with the "better idea". In short, don't make it complicated.
Simtec also has a filler if you are using their products.
Lane
On Tuesday, April 4, 2017 at 10:53:46 AM UTC-4, wrote:
> Go with Hanks advice. He guided me in the refinish of CF and it turned out great. I was constantly advised by spectators as to how I "should do it". One guy grabbed a gear foot and promptly sanded through to the foam core. From then on I didn't mind being rude to the next neighbor with the "better idea". In short, don't make it complicated.
>
> Simtec also has a filler if you are using their products.
>
> Lane
Simtec 2081 does not sand anywhere as well as Polyprimer. JJ put me on to Polyprimer.
UH
Papa3[_2_]
April 4th 17, 07:25 PM
I'll second (actually third) Hank's recommendation. I'm now a disciple of UH and Church of the Holy Pinhole.
Our club tends to wait until the existing gelcoat approximates the look of a dessicated mud flat before we start a refinish. So, almost all the old gelcoat ends up coming off, which results in PINHOLE HELL. After following Hanks advice on last year's LS4 project, I could count the number of pinholes with hands and toes, as opposed to prior jobs where we spent several cycles trying to spray our way out. This year's Grob Fuselage had a couple of pinhole fields only because I was sloppy on the prep work.
In terms of prep, I supplement the air blowing with a wipe down using a lint-free rag and either Prep All or Acetone.
I'll add that a really soft rubber scraper used to squeegee the Polyprimer into really bad pinhole fields seems to work even better than the roller if you are careful. We sometime roll then go over with the scraper working back and forth a few times.
P3
On Tuesday, April 4, 2017 at 11:56:12 AM UTC-4, wrote:
> On Tuesday, April 4, 2017 at 10:53:46 AM UTC-4, wrote:
> > Go with Hanks advice. He guided me in the refinish of CF and it turned out great. I was constantly advised by spectators as to how I "should do it". One guy grabbed a gear foot and promptly sanded through to the foam core.. From then on I didn't mind being rude to the next neighbor with the "better idea". In short, don't make it complicated.
> >
> > Simtec also has a filler if you are using their products.
> >
> > Lane
>
> Simtec 2081 does not sand anywhere as well as Polyprimer. JJ put me on to Polyprimer.
> UH
Bob Kuykendall
April 4th 17, 11:59 PM
We nuke about an ounce of epoxy in the shop microwave until it is almost too hot to hold, then quickly squeegee it across the pinholed surface so it forms a meniscus that fills in the square corners of each pinhole. An ounce covers like 10-20 square feet. We generally do that twice, and then sand the remaining epoxy off and fill the remaining weak depressions with Duratec.
I use the soft squeegee and polyprimer to good effect. Something else that helps is to get the wing hot and then prime it. Allow to cool. The cooling seems to suck the primer down into the microvoids as the air in them cools and thus decreases its volume, creating a slight vacuum.
Fidel, actually pulled a slight (2-3"hg) on my wings. Then spread thinned out epoxy on the surface over the multitude of pinholes. Cured it and then tested it with 3-4 ft of head pressure with water worked great and the completed the refinish😀 No leaks so far that was about 8 years ago?
Bob Kuykendall
April 5th 17, 09:27 PM
On Wednesday, April 5, 2017 at 7:19:17 AM UTC-7, wrote:
> Fidel, actually pulled a slight (2-3"hg) on my wings...
I'm going to remember that trick; it sounds like a great way to address the leaky bondlines that I've heard of on early LAK-17. But I imagine that if your vacuum regulator slipped you could make a mess of a wing in a real hurry.
--Bob K.
On Tuesday, April 4, 2017 at 10:18:43 AM UTC-4, wrote:
> After removing all the gelcoat, a friend recommended applying a very thin cloth known as Vail to fill most pinholes. We brushed on epoxy and rolled on the Vail, followed with thin peal-ply, then squeegee'd it out with excess resin toward the trailing edges of the wing. Not sure it worked all that well and took two of us 4 hours + $400 bucks for Vail, resin and peal-ply. In some areas (near spoilers), we trapped some resin between the Vail and peal-ply which was full of pin holes!
> I think the concept is good, but next time I believe I'll skip the Vail and just brush on epoxy and cover it with peal-ply. The resin has got to fill most pin holes and the peal-ply will leave the surface ready to prime.
> Would like to know what others are doing?
> JJ
Simpler and Cheaper method, used at one of the most well known refinishers in the country: blow stripped wing off very well to clear voids in glass. when filling /priming with 2081 (or your filler of choice), just before spraying, start by mixing up a small batch of filler, and squeegee it onto the wing (or whatever) with a plastic bondo spreader. it fills the holes, improves the bond, doesn't add measureable weight, and the incremental cost is a few cups of filler.
On Tuesday, April 4, 2017 at 11:56:12 AM UTC-4, wrote:
> On Tuesday, April 4, 2017 at 10:53:46 AM UTC-4, wrote:
> > Go with Hanks advice. He guided me in the refinish of CF and it turned out great. I was constantly advised by spectators as to how I "should do it". One guy grabbed a gear foot and promptly sanded through to the foam core.. From then on I didn't mind being rude to the next neighbor with the "better idea". In short, don't make it complicated.
> >
> > Simtec also has a filler if you are using their products.
> >
> > Lane
>
> Simtec 2081 does not sand anywhere as well as Polyprimer. JJ put me on to Polyprimer.
> UH
2081 sands fine if you add a little gelcoat. i'd be interested to try polyprimer sometime.
Bob Kuykendall
April 6th 17, 10:49 PM
> ...start by mixing up a small batch of filler, and squeegee it onto the wing (or whatever) with a plastic bondo spreader...
The problem I and others have had with that approach is that the filler does not wet out the surface of the pinhole very well. Even though it fills the pinhole, it does not establish a bond with the surface. Often, the pneumatic pressure of the air in the pinhole forces the thick filler back out, so you get only a very shallow fill over the top of the pinhole.
As it ages and the wing (or whatever) flexes, the filler is likely to break free from the interior surface of each pinhole. Then the pinholes start mirroring through the finish paint, and eventually might start cracking in a checkerboard pattern.
Squeegeeing on a couple quick skims of runny epoxy helps wet the interior surface of each pinhole, and forms a rounded meniscus over its sharp irregular internal contour. Filler sprayed or squeegeed over the epoxy skim has a better surface to bond to, and there is less internal volume in each pinhole for air that repels the filler and impedes the bond.
--Bob K.
I'm with you, Bob! That's why I think I'd brush on an epoxy coat (maybe squeegee'd) and then peal-ply everything, so she's ready to accept prime without any sanding needed. OBTW........please shoot me if I ever take on another re-finish job! My son and I bid a set of LS-6 wings at $40/hr................we got $25/hr
NEVER AGAIN
JJ
On Thursday, April 6, 2017 at 5:49:39 PM UTC-4, Bob Kuykendall wrote:
> > ...start by mixing up a small batch of filler, and squeegee it onto the wing (or whatever) with a plastic bondo spreader...
>
> The problem I and others have had with that approach is that the filler does not wet out the surface of the pinhole very well. Even though it fills the pinhole, it does not establish a bond with the surface. Often, the pneumatic pressure of the air in the pinhole forces the thick filler back out, so you get only a very shallow fill over the top of the pinhole.
>
> As it ages and the wing (or whatever) flexes, the filler is likely to break free from the interior surface of each pinhole. Then the pinholes start mirroring through the finish paint, and eventually might start cracking in a checkerboard pattern.
>
> Squeegeeing on a couple quick skims of runny epoxy helps wet the interior surface of each pinhole, and forms a rounded meniscus over its sharp irregular internal contour. Filler sprayed or squeegeed over the epoxy skim has a better surface to bond to, and there is less internal volume in each pinhole for air that repels the filler and impedes the bond.
>
> --Bob K.
that has not been my experience. it's worked pretty well for me for the last several years, during which time i've done a few dozen refinishes. also, filler seems to be less viscous than runny epoxy. and you can spray right over, immediately afterwards without any sanding. i also believe that it does create a good bond, especially since there is a mechanical bond in there. i have not had any problems with filler pushing back out of the pinholes. in fact, there is a soft of capillary action, and it seems to soak in like a sponge. i remember doing a wingtip that was heavily crazed, by squeegeeing some resin. it was messy, and not so nice to sand afterwards. no question, your method works well, but i think mine does too. there advantages to both.
Let me pass on a good trick to deal with Kevlar fuzz. If you accidentally sand into a Kevlar layer, you find it won't sand, it just fuzzes up! We soaked the exposed Kevlar with CA (cyanoacrylate) from the local hobby shop, then hit it with Fix. This left it stiff as a board and simply scrapped most of it off with a sharp razor blade.
Also had raw Kevlar exposed at the trailing edge of flaps and ailerons. These areas must be sealed up or the Kevlar will "wick" in moisture! We got some 1 oz fiberglass tape (1" wide) and 1" peal-ply. Wet it out and wrapped it around the trailing edges, held in place with masking tape orientated for/aft.
JJ
On Friday, April 7, 2017 at 8:49:33 AM UTC-4, ND wrote:
> On Thursday, April 6, 2017 at 5:49:39 PM UTC-4, Bob Kuykendall wrote:
> > > ...start by mixing up a small batch of filler, and squeegee it onto the wing (or whatever) with a plastic bondo spreader...
> >
> > The problem I and others have had with that approach is that the filler does not wet out the surface of the pinhole very well. Even though it fills the pinhole, it does not establish a bond with the surface. Often, the pneumatic pressure of the air in the pinhole forces the thick filler back out, so you get only a very shallow fill over the top of the pinhole.
> >
> > As it ages and the wing (or whatever) flexes, the filler is likely to break free from the interior surface of each pinhole. Then the pinholes start mirroring through the finish paint, and eventually might start cracking in a checkerboard pattern.
> >
> > Squeegeeing on a couple quick skims of runny epoxy helps wet the interior surface of each pinhole, and forms a rounded meniscus over its sharp irregular internal contour. Filler sprayed or squeegeed over the epoxy skim has a better surface to bond to, and there is less internal volume in each pinhole for air that repels the filler and impedes the bond.
> >
> > --Bob K.
>
> that has not been my experience. it's worked pretty well for me for the last several years, during which time i've done a few dozen refinishes. also, filler seems to be less viscous than runny epoxy. and you can spray right over, immediately afterwards without any sanding. i also believe that it does create a good bond, especially since there is a mechanical bond in there. i have not had any problems with filler pushing back out of the pinholes.. in fact, there is a soft of capillary action, and it seems to soak in like a sponge. i remember doing a wingtip that was heavily crazed, by squeegeeing some resin. it was messy, and not so nice to sand afterwards. no question, your method works well, but i think mine does too. there advantages to both.
I've seen some times when trapped air pushes the filler back out of the pinhole to some degree. The reason I went to the roller method is that each individual area gets multiple passes from at least 2 different directions which I have found minimizes this. I also have found that I can get a more uniform surface with the roller than I can with a squeegee. I've done it both ways and still occasionally find that the squeegee helps.
Sanding this filler back flat does no new damage to the surface where sanding epoxy is harder and, I have found, more prone to adding more damage.
I have not seen any pinhole repairs come back to the surface with this technique.
It's worth noting that there are several ways to skin this cat.
UH`
JJ and Uncle Hank, do you shot PPG Concept right over the polyprimer or do you use a PPG primer also?
Thank you
On Saturday, April 8, 2017 at 8:09:09 PM UTC-4, wrote:
> JJ and Uncle Hank, do you shot PPG Concept right over the polyprimer or do you use a PPG primer also?
> Thank you
I seal with epoxy primer. I think JJ goes direct based on his prior comments.
I have done it both ways, but prefer polyprimer because it is white!
Another tid-bit I have tried is to wet sand with 800 grit after 12 to 24 hours cure, then buff out right away. Shines like no tomorrow, believe the paint is moving under buffer, just enough to eliminate the 800 sand marks.
JJ
Charlie M. (UH & 002 owner/pilot)
April 9th 17, 03:51 PM
The difference in heat between "flowing the paint" and burning it is a close one. When I do final polish wax, I like to get it warm on the surface with polishing load. It gets a nice shine.
On Sunday, April 9, 2017 at 9:35:00 AM UTC-4, wrote:
> I have done it both ways, but prefer polyprimer because it is white!
> Another tid-bit I have tried is to wet sand with 800 grit after 12 to 24 hours cure, then buff out right away. Shines like no tomorrow, believe the paint is moving under buffer, just enough to eliminate the 800 sand marks.
> JJ
The extra step I now do with white epoxy primer makes me more comfortable that I have a really good surface before I spray finish. I put disclosure coat on and wet sand with 400. I find that, for me, it avoids unhappy surprises. It does add more time for sure.
I sand the paint out with 1500, then 3000, then buff. I sand on the 3rd day, or later. JJ's methods are quite a bit faster.
Not sure what Andy and Heinz are doing.
FWIW
UH
Would someone share what is the PPG Concept paint color code refinishing shops use. I assume there is no ASW-24 or Discus white! Thank you
On Sunday, April 9, 2017 at 6:26:35 PM UTC-4, wrote:
> Would someone share what is the PPG Concept paint color code refinishing shops use. I assume there is no ASW-24 or Discus white! Thank you
Heinz told me he uses PPG Concept 91370 Renault Blanc San Carlo. "Matches Simtec 2481 perfectly".
On my '29 I used pure white base with no other tinting. I know I can match that.
UH
Pure white (aka mixing white) PPG, DMC 900 $434.25/gal if you please!.........Genesis-2 is the only manufacturer that I've seen who specified a Toyota color.
JJ
Michael Opitz
April 10th 17, 01:02 AM
At 22:26 09 April 2017, wrote:
>Would someone share what is the PPG Concept paint color code
refinishing
>shops use. I assume there is no ASW-24 or Discus white! Thank you
>
How big an area do you need to paint? As opposed to going through
all of the pain and expense of the 2 part epoxy gel-coats and paints,
I have opted to use Duplicolor Auto Lacquer spray bombs to paint small
touch up areas. The color that I have found best matches the older
Schwabelack on our Twin Astirs is Ford Performance White at about $8
per spray can. I use some primer first, and then 4-6 thin coats of the
lacquer, making sure it is tack dry in between coats to avoid runs.
Once the last coat is dry, I'll wet sand with 600-800-1000-1500-2000
and then buff to a high gloss. It may not be an absolute perfect
match, but it is pretty quick and easy, and I have found that the color
matches pretty darn closely..... I can totally re-do small areas from
start to finish in just a few hours.
RO
ND
April 10th 17, 03:18 PM
On Sunday, April 9, 2017 at 5:37:59 PM UTC-4, wrote:
> On Sunday, April 9, 2017 at 9:35:00 AM UTC-4, wrote:
> > I have done it both ways, but prefer polyprimer because it is white!
> > Another tid-bit I have tried is to wet sand with 800 grit after 12 to 24 hours cure, then buff out right away. Shines like no tomorrow, believe the paint is moving under buffer, just enough to eliminate the 800 sand marks..
> > JJ
>
> The extra step I now do with white epoxy primer makes me more comfortable that I have a really good surface before I spray finish. I put disclosure coat on and wet sand with 400. I find that, for me, it avoids unhappy surprises. It does add more time for sure.
> I sand the paint out with 1500, then 3000, then buff. I sand on the 3rd day, or later. JJ's methods are quite a bit faster.
> Not sure what Andy and Heinz are doing.
> FWIW
> UH
When it comes to PU, I give the paint some time. like 2-3 days. i find that if you try and sand the day after painting, it's too soft. then i cut the orange peel with 800 using diagonal strokes. after that it's spanwise sanding with a soft finishing block in 800, 1000, and 1500, then buff. i find that buffing usually needs to wait at least a week after paint application, otherwise you get crescent shaped streaks in the finish, from the polishing wheel gouging the paint.
Uncle Hank, will you share the brand and product number for the epoxy primer you use?
Thank you
On Monday, April 10, 2017 at 8:37:58 PM UTC-4, wrote:
> Uncle Hank, will you share the brand and product number for the epoxy primer you use?
> Thank you
The epoxy primer I use is made by Transtar. I'm travelling and don't have the numbers. It is available in white, buff, gray, and black. I use white. It looks pretty damn nice even before I spray color.
UH
Charles Waldo
April 13th 17, 05:39 PM
Just redid my wings with Hank. Here is the primer he had me order....
Web address http://www.autorefinishsupply.com/
Product:PCL907-GL PCL Poly Primer White - Gallon
On Thursday, April 13, 2017 at 12:39:49 PM UTC-4, Charles Waldo wrote:
> Just redid my wings with Hank. Here is the primer he had me order....
>
> Web address http://www.autorefinishsupply.com/
> Product:PCL907-GL PCL Poly Primer White - Gallon
That is the polyester surface filler. This is followed by epoxy primer when painting with AU,
UH
I just spot sprayed 3 areas with Concept AU after modifying the root rib area IAW the Salve modification to the Genesis-2. I let the paint cure for 2 days, because parts were sticking out of the shop and I couldn't close the doors to heat the shop (70 day/40 nite). Today I wet sanded it out with 600, then buffed the new paint out with liquid buffing compound (with water) and a wool buffing pad. The 600 scratch marks are completely gone and the paint has a high luster with only one buffing. However, the sanding scratches in the old paint (in the blend area) are quite visible and I was forced to remove them with traditional methods, 800, 1000 then several buffing passes with increased pressure and adding water to the buffing compound to increase the cutting action on the old hard paint.
So, what does this mean? Countless hours can be saved on a complete re-finish job by sanding the paint out while it is quite new and green enough that the 600 scratch marks are completely removed by the cutting action of the buffing pad and compound + water.
JJ
JJ, perhaps the polishing compound that you are using is key. Can you share what you are using?
On Thursday, May 11, 2017 at 7:01:41 PM UTC-4, wrote:
> I just spot sprayed 3 areas with Concept AU after modifying the root rib area IAW the Salve modification to the Genesis-2. I let the paint cure for 2 days, because parts were sticking out of the shop and I couldn't close the doors to heat the shop (70 day/40 nite). Today I wet sanded it out with 600, then buffed the new paint out with liquid buffing compound (with water) and a wool buffing pad. The 600 scratch marks are completely gone and the paint has a high luster with only one buffing. However, the sanding scratches in the old paint (in the blend area) are quite visible and I was forced to remove them with traditional methods, 800, 1000 then several buffing passes with increased pressure and adding water to the buffing compound to increase the cutting action on the old hard paint.
> So, what does this mean? Countless hours can be saved on a complete re-finish job by sanding the paint out while it is quite new and green enough that the 600 scratch marks are completely removed by the cutting action of the buffing pad and compound + water.
> JJ
i'd be curious to see the finished piece, i don't like the idea of "burnishing" soft paint (IE moving paint material to fill scratches.) i just feel like i could get it much smoother by hand. also, I begin PU with 800, and after doing a similar amount of sanding to what you are doing with 600, there really not much more sanding after that. you do have to step through 1000 then 1500 doing it my way, but its pretty quick. it's certainly not hours and hours, especially not for something small like the wingroot mod on a genesis. in any case, i love the luster and finish quality of gelcoat, but i much prefer working with PU. it's much less sanding!
I usually start with 800, but accidentally got a quarter sheet of 600 mixed up with 800 and was surprised to see the big scratches in the old paint in the blend area. But this showed me that the new paint that had been sanded with 600 showed no scratch marks after buffing. I have seen two ways to buff out sanded paint, the "dry" method picks up a bit of compound and buffs out a small area. I was shown the "wet" method by an old car painter where I squeeze out a ribbon of compound about 3 feet long, then dip 2 square inch rag in water, squeeze it a bit and then spread out the ribbon to make the area about a foot deep X 3 feet long. Starting with a 4" bite, I make repeated passes left to right starting with increased pressure, the backing off the pressure until I not have only the weight of the buffer pressing down as the luster shows through. More cutting in obtained by increasing pressure and/or, by using more water. I use 3M rubbing compound. E-mail me at johnsinclair210(at) yahoo.com and I'll be glad to send you photos of a couple ships finished by sanding out Concept Acrylic Urethane while the paint was quite new.
JJ
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