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I've never been happy with using any patch material on HDU, for filling dings and scratches. Anywhere there is a patch, the area remains "solid" instead of porous like the HDU. This results in a glossier area where the patch is. I've used spackling, body filler, body putty, I even tried to add some HDU "dust" to spackling, to no avail. Even tried using foam adhesive and foam insulation. No good. Someone out there has the answer!!!
-------------------- Gene Golden Gettysburg Signs Gettysburg PA 17325 717-334-0200 genegolden@gettysburgsigns.com
"Art is knowing when to stop." Posts: 1578 | From: Gettysburg, PA | Registered: Jun 2003
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Gene, I haven't found a way to duplicate the porous HDU either. Try priming the damaged area first. Then use your bondo or spackling. Then sand and feather it out. Then prime again, sand again. I've done them before where you couldn't find the "shiner" at all.
-------------------- Wayne Webb Webb Signworks Chipley, FL 850.638.9329 wayne@webbsignworks.com Posts: 7403 | From: Chipley,Florida,United States | Registered: Oct 1999
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Usually I will patch HDU after the 2nd coat of primer. The smoother it is before you patch the less noticable it will be. My normal finishing on sign foam is block sand 120-220, blow off,roll 3-4 coats of sign prime, sand with 120 to get most of the orange peel then 220, tack and paint. I like it really smooth some people don't. I hate to drive by and be able to tell it's foam by the crappy paint job.(I know I'm an anal sign person and the average guy wouldn't notice) Sounds like alot but it really isn't.
-------------------- Eric PA Posts: 149 | From: Intercourse, PA | Registered: Jun 2004
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Use Coastal Enterprise crack/dent filler on the entire panel, applied with a wide spackle trowel. This will fill the voids in the hdu surface. If your scratch is too deep for one coat, add another until it's filled. Then sand the whole thing smooth. You CANNOT match a patched area with raw foam, but you can "patch" the entire panel, so that when you sand it smooth, you are sanding the filler insteas of the hdu.
-------------------- "A wise man concerns himself with the truth, not with what people believe." - Aristotle
Cam Bortz Finest Kind Signs Pondside Iron works 256 S. Broad St. Pawcatuck, Ct. 06379 "Award winning Signs since 1988" Posts: 3051 | From: Pawcatuck,Connecticut USA | Registered: Nov 1998
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Gene, here is a method I used recently to fix a goof-up I did on an HDU sign.
This first photo shows the groove (originally a "v" groove) I routed in the wrong place. (you can see the guide lines to the left I should have been in). I re-routed it with a flat bottom bit.
The next photo shows a "key" I cut-out on the table saw. I kept it as tight as I could, and let it sit a little proud (high) of the surface.
The last photo shows the "key" epoxied, and sanded flush. The slight imperfections aroung the edges were easily filled in with primer. It was barely noticible, even if you were looking for it.
This works well for a major mistake, but could also work well with a big "ding" or heavy scratch.
I agree that it never seems to match if it's filled with bondo, or the likes.
Good luck, Bob K.
-------------------- "The 3-4 minute mark of "Freewill" by Rush.
Bob Kaschak Artisan Sign And Design Peru New York Posts: 1873 | From: Upstate NY | Registered: Jul 2002
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For small scratches and dings try Baking soda and super glue put some powder in the scratch then a drop of super glue. You will see a small puff of smoke and walla instant patch sand smooth and finish normally.
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here is something I noticed most recently regarding this subject. I previously due to costs was using Precision Board HDU products. When I would fill any voids or damaged areas with wood filler, and then prime and paint, I would get the exact thing as you folks are talking about. The repair would be glaring at me like a sore thumb. I then incidentally switched over to Sign Foam and I do not have anywhere near the issue as I had in the the past. I actually kept the sample of PB around the shop to show people who visit me or my students the difference in the product and why it is worth the difference in price.
Another neat thing that I am thoroughly enjoying about sign foam is that it is a consistant thickness through out the 4 X8 sheet rather than the eigth inch variation of PB. On a positive note about PB though, is that glen who works for them is a stand up guy and will do anything he can in his power to help you out. Dale
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I'm absorbing all of these suggestions. Some I can try now, others I will keep in the deep recesses of my mind. Unfortunately, it seems easier to repair a large mistake than it is to fill dings. And yes William, I agree, I just gotta try that baking soda trick!
Bob, I used that trick once to replace an arrow on the backside of a sandblasted sign that pointed the wrong way (well ONE of them was pointing the right way).
Any other suggestions will be welcome. Thanks for these.
-------------------- Gene Golden Gettysburg Signs Gettysburg PA 17325 717-334-0200 genegolden@gettysburgsigns.com
"Art is knowing when to stop." Posts: 1578 | From: Gettysburg, PA | Registered: Jun 2003
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Spackle that you use on sheet rock works good too-just prime over very well after sanding. Also sometimes you can use a urethane based glue(gorilla, probond, etc...) to patch a stubborn area. It will foam up over the edge of the hole and can be sanded back off at the same rate as the HDU. Play around with it first on some scrap to learn the results. Good Luck. John M.
-------------------- John P Meeks The Sign Shoppe, Inc. Everwood 200 Brozzini Ct. Greenville, SC 29615 864-275-5140 Posts: 44 | From: Greenville, SC | Registered: Oct 2004
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just thinking outloud here, but I have had the same problem many times. This idea just popped in the ol' noggen. How about using a hole saw on a drill press without the center drill bit, to make a foam plug. Then drill a hole in the sign with the same size ID as the OD of the plug, and glue the plug in with gorilla glue. All you would have is a small ring to contend with, and if the plug were really tight it shouldn't even be noticeable. Again, jus thinking out loud.
-------------------- Dave Utter D-utterguy on chat Sign Designs Beardstown, Il. signdesigns@casscomm.com Posts: 777 | From: beardstown, illinois, usa | Registered: Mar 1999
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You all gotta try William DeBekker's super glue trick!!! I don't know if it actually paints without a gloss spot but WHO CARES? I had to go buy some new glue 'cause mine was all dried up of course. Then I spent 20 minutes dropping the stuff onto the Baking Soda... now I gotta buy some more glue. Smoke puff... puff...puff... don't huff. It looks better if there is a dark backdrop to see the smoke.
Okay now for another test. I dug some decent sized 1/4" gouges and small scratches into 18# HDU. I modified William's great idea, and tried it with fine salt (the leftover packets from McDonald's). It's not as fun, no puffs of smoke, but I think this may be another way to go. What I did is: sprinkled the salt onto the scratched/dented area FIRST. I figure that any open pores will be blocked by the salt, preventing them from filling with adhesive. Then I dripped the Superglue onto the areas that were scratched. It filters its way through and around the salt. After it cured, I took a chisel, and sliced the raised areas flat to the board. Technically, there are now particles of salt encased in Superglue. After shaving and sanding it level, it exposes grains of salt (the glue encases it, doesn't dissolve it). Since the salt is water soluable, I soaked the salt with water and scrubbed away with a toothbrush. The salt had acted as a "resist" and where it washed out little "pores" remained. Under a magnifying glass, it's very convincing. I'll keep you posted on how the paint test goes. I'm impressed so far.
-------------------- Gene Golden Gettysburg Signs Gettysburg PA 17325 717-334-0200 genegolden@gettysburgsigns.com
"Art is knowing when to stop." Posts: 1578 | From: Gettysburg, PA | Registered: Jun 2003
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I don't work much with HDU but I know someone who patches, smooths out the filler and then applies a piece of sandpaper, rough side down, over the patch. Once set up, the sandpaper is removed. She says she is able to duplicate the texture quite well. I think she uses an exterior grade spackle.
-------------------- David Harding A Sign of Excellence Carrollton, TX Posts: 5084 | From: Carrollton, TX, USA | Registered: Nov 1998
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