ConcoursMustang Forums
Restoring - General discussions that span across many different groups of years and models => Body, Paint & Sealers => Topic started by: MustangAndFairlane1867 on August 25, 2017, 08:25:52 PM
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One of the original doors on my '65 Mustang has a dent about the size of a 50-cent piece on the inside, bottom of the door. There's no way to get behind the dent for repairs, which seems to mean that a filler is the only option I have to fix it. The problem with that, of course, is the repaired area will then be smooth and without that attractive "fabric?" pattern that is stamped in the metal all the way around the door. I recall many years ago reading (Mustang Monthly, maybe) of a way to closely duplicate that pattern after a repair is made using a bondo-style filler, but I haven't been able to find the source anywhere. I want to save this otherwise-nice original door, but I don't want to jump into the repair until I have a plan and maybe some suggestions on how best to do it. I've painted the interior of these doors before, so I know about the necessity to sand gently and apply the paint lightly so as not to obliterate the "fabric" pattern. Sure would like to hear from owners who have "been there, done that." Many thanks. Ron
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Ron
Can you post a pic of the dent showing where it is so everyone has a better understanding
Cheers
Peter
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Once you strip the door or a donor door of all the paint from the textured area you can make a mold with silicon of the texture. Once you fix the area (since its pretty small) and apply filler you can apply the mold. remove it then join the "lines" pattern carefully with a toothpick then once dry knock down any material that was pushed up through the process. Practice a number of times first before the final. Also clean, clean and clean again the surface if you used your project door to make sure any silicon is gone our you'll curse yourself later.
Just one way some have made it work
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Once you strip the door or a donor door of all the paint from the textured area you can make a mold with silicon of the texture. Once you fix the area (since its pretty small) and apply filler you can apply the mold. remove it then join the "lines" pattern carefully with a toothpick then once dry knock down any material that was pushed up through the process. Practice a number of times first before the final. Also clean, clean and clean again the surface if you used your project door to make sure any silicon is gone our you'll curse yourself later.
Just one way some have made it work
There are so many better products to use as a molding compound, I doubt I (personally) would use ANYTHING silicone. (Silicone is the 'Enemy' of any painter).
Several years ago, I purchased a "Plastex" branded, plastic repair kit with something called a "molding bar" included to form the shapes of missing parts and/or textured surfaces. ANYTHING along those lines (IMHO) should be a MUCH BETTER choice than ANYTHING silicone. Again, my opinion. I have not tried to duplicate this texture on steel surfaces, so if other's recommendations work...I certainly do not wish to discredit their advice. ...but YES, if silicone is used...CLEAN, CLEAN, CLEAN afterwards!
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I think I've posted before on this...but I've used 3M rocker spray (The green label I think...it dries harder and faster) to spray a texture coat on the repaired area then knocked the top off with some fine sandpaper.
Try it on an area first though. It worked for me. Far from perfect but worked well after repairing some speaker holes.
I will need to do it again, as I have a perfect rust free right door shell with a nice dent in the interior door my granddaughter put in there for me. Ugh.
If I can find a can out in the shop I'll try to duplicate it and snap a few pics.
SamG
Yes I know it's an old post but I've not been around in a while.
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Sam, looking forward to seeing your repair. I just finished a 67 Coupe that took me weeks to fit the repo doors. I would prefer to fix my originals.
Mark
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I just repaired a section of my 67 SJ car door that required grain.
First, I agree that silicone is the enemy of paint. My painter will not allow me to bring in any part that has any silicone on it -- ever.
My wife loves making molds, mostly of garden art forms. She has done this for over a decade and uses liquid latex almost exclusively for the master mold. Mother molds are another topic and not needed here.
I brought over a 3' long heat source (infrared or strip) and brought the area to 70-80*.
Liquid latex is simply brushed on an area of the door that you wish to use as the grain template. I use an area of about 4"x8". I first go horizontally and let the area dry and become darker. Then vertically and then diagonally. I go up to about 5 or 6 coats.
I let the area sit for a few hours and then add baby powder to the side facing.
The template is then flipped over and baby powder applied there.
The result is a mold that is extremely flexible.
If you want a mold with more rigidity add a layer or two of cheesecloth as the final two steps. For my door fix the extra rigidity was a detriment, so I used only latex.
I first got the area very close to the original form with metal. In my case rust had eaten through parts of the corner. The area in question then had a 2K primer applied and allowed to dry for days. I brought the area up to a decent temperature (mid 70s) with the heat source and applied a very thin and even layer of filler. I made sure the filler did not go much beyond the blank area by using blue tape. The mold material was then wrapped around this area and tapped in position to keep it static.
Use a paint stick, bondo spreader or other forms to press the mold into the bondo. My area was curved and present a much different set of issues than a flat area -- which should be much simpler.
After the bondo has kicked you can remove the mold material and use dental picks or other tools to meld in areas not quite perfect.
Wash the mold with thinner to remove any remaining material and repeat the dusting of baby powder -- spread it around with your hand.
This requires a lot of patience and you will not get it right the first time. This is tedious, so be ready for that.
I'll post a pic of the finished product, but due to my door's complex shape I've done each surface as a separate run and have one or two (out of six) areas left (before I had back issues, again).
Here is a shot of how one curve was done.
[edit stupid grammatical errors]
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I think I've posted before on this...but I've used 3M rocker spray (The green label I think...it dries harder and faster) to spray a texture coat on the repaired area then knocked the top off with some fine sandpaper.
My painter was doing some paint match on a spare door I brought him and did this same thing.
On edit, here is a pic of this texture, unsanded.
Decent fix for a daily driver.
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Looking forward to seeing the result of the latex mold....I think I would like to try that.
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It's hard to make out the grain unless you paint it and I'm not ready for that on the door.
Here is one of my first tests to see how the grain looked. This is your standard body filler -- a Wesco in-house brand. I made little effort to blend the filler into the surrounding area. The test piece was painted with just a light fogging of semi-gloss black so I could actually see the grain.
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That looks nice. The main challenge will be blending with the surrounding area. It would be best to leave as much of the original door grain as possible intact. Use hard tape, like aluminum backed on the surface of the door and fill from the backside. This works well for small pin holes after any rust has been removed/neutralized.
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That looks very promising.
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I'm waiting for my back to feel better ...
But, I did experiment with adding various ingredients to the filler to make it less viscous (not working) and using vacuum bagging in order to put equal and higher pressure on the latex.
The later has merit but I'm fighting with 'vacuum pump mist' (google it) as I don't want to breath vaporized oil.
Since the filler I'm using is too stiff I've ordered some more 3M 31180 Finish Glaze. The batch I had went bad after sitting too long. The idea is to build up the general repair area with filler, but to later impregnate the pattern using a very high quality glaze. The pattern need not be very deep and glaze can be very thin. It's a bit runny, which is a good quality for this repair. It's also a 2 part, so it hardens quickly.
Just in case you want to experiment with vacuum bagging, the idea is simple.
Adhere a plastic film around your repair area with duct tape or similar sticky tape and apply vacuum.
To get a vacuum source into the film I stole a screw-on schrader valve from one of the race car wheels. I then added two large washers and two large rubber washers to the mix. Cut a hole in the film and sandwich the film between the rubber washers and tighten the whole affair.
See https://www.veneersupplies.com/products/Bag-Stem-Assembly.html
Although I have a real A/C pump (garage sale) a compressor from a fridge works too. HF also sells them. Various fittings and an old R-12 A/C gauge set round out the tools.
Apply your filler to the repair, tape the latex in place, cover the area with your vacuum film and tape and then apply vacuum.
Do note that in this pic that the vacuum valve is too close to the repair.
Also, I may need a mat to place over the latex in order for the vacuum to be distributed over the enter area. Look up 'composite vacuum bagging' to learn more.
I'm not saying this is the final answer, just some thoughts on how to progress towards one solution and get those smart minds out there working.
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When I was a designer/lab technician back in the mid 60's, I help developed a procedure using a vacuum chamber to draw a special epoxy resin into wire wound coils used in certain specialized electronic components called delay lines. The theory was the lower pressure would remove small pockets of air in and between the coils and other components. The pockets would expand, "burst" and be filled with the resin when the air pressure was returned to normal. It worked well in lab tests, and a larger chamber was used in production. The technique Bill is using is similar, draw out the air and fill the void with filler. You need to draw at least 28 some inches of Mercury, that's air pressure under 1 psi, and hold it for a couple of minutes to be effective.
To "test" the effectiveness of the vacuum chamber, flies were captured, placed in the chamber, and then "vacuumed". Surprisingly, many survived. They did not fly in the chamber, but when normal air pressure was returned, they flew away. There is no truth to the rumor that a mouse was a test subject.
Jim
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Depending on where the repair is located, maybe a bag of water would work as a "weight". Orientate the majority of the patch normal to the force of gravity and position the bag of water. The pressure would distribute relatively evenly, etc. This method might also take a little less time to get positioned and activated - time is not in your favor with any finish glaze.
I really like your concept BossBill!!!
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On a flat surface any full surface weight will work to some extent. I'm trying to prevent any shifting of the latex and to spread the filler or glaze out far enough so that there is little or no edge.
This really became an issue with the curved edges at the bottom of the door.
The inward curves were really tough. It's hard to keep the latex in contact with the filler while it dried.
That's where vacuum comes in handy -- to have the pressure differential push the latex into the curve and especially where the weatherstrip is glued.
Plus, the pressure applied to the surface is hard to beat without a vacuum.
12–25 inches of mercury equals 6–12.5 psi on the latex. This pressure is almost impossible to duplicate without "clamping".
http://www.westsystem.com/wp-content/uploads/VacuumBag-7th-Ed.pdf
Section 1.2
I should add that another benefit is one that Jim mentioned. Vacuum will draw out entrapped air. This works well for removing air bubbles from urethane (and other media) poured into a mold -- and from glaze.
After a week of trying I've found this to be very difficult on curved surfaces. After half a dozen tries I have one surface that is tolerable for the bottom of the door. The vacuum system does not work as well as I had hoped as it leaves a wavy surface.
A brayer (roller) is working better.
More updates later.
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Bill, have you had any updates to your technique?
I have repaired a bottom of my driver's door, fortunately, only some small areas to work on that can be seen beyond the weatherstrip.
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I'll find a pic of my finished repair.
I've modified how I do this now as it has taken literally dozens of attempts to find something that works. Be aware that this tends to work best on small areas.
I make a thin latex mold of a good area -- roughly a 4x6 area. Make sure the back is as smooth as possible.
Mix 90% isopropyl alcohol (or Everclear!) with caster oil in a 4:1 ratio and spread on the latex pattern. This is actually the key as it's a mold release and will not allow the bondo to stick to the latex.
Mix up a small amount of finish glaze (finesse bondo).
Spread very thin on the area in question. I use a razor blade or other blade and spread very smoothly. Leave no lines.
Apply the latex. I use tape to keep it from moving around.
I used a rubber roller to roll over the surface of the latex. You do not want to roll hard enough that the latex moves.
Leave the latex on until the glaze kicks. Use a wax and grease remover to remove the castor oil.
An improvement I thought about for very flat areas was to lay the latex flat and to apply some bondo (or other thick adhesive) to the back side. Squish a piece of wood into the bondo. This should turn the latex into a stamp.