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Shutter fabric "recoating" idea- need sanity check
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semihemi



Joined: 25 Oct 2003
Posts: 85
Location: Boston, MA

PostPosted: Mon Dec 28, 2009 4:56 am    Post subject: Shutter fabric "recoating" idea- need sanity check Reply with quote

For whatever reason I have completely abandoned all family and social activities and I have holed up in the basement with a case of Odwalla bars and a bunch of Graflex SLR projects. Tonight's flight of madness was the transplant of a good shutter curtain from a partially crushed Auto to another camera with no mechanical issues other than a rather crispy shutter curtain. All went well and I am now in the final phase of every Graflex rebuild: replacing missing screws and filling stripped holes. However, at the end of it all I found myself with the dead shutter curtain in my hand. Just for giggles I held it up to a light to see if it was just stiff or if it also had light leak issues. Turns out it had plenty of pinholes right along those horizontal striations that characterize moribund shutter curtains. But while I was looking at it so closely I noticed that aside from the brittle rubber, the rest of the curtain was in fabulous condition. The metal spars were perfect and the fabric (not the rubber) was just as supple and pretty as the day it was born. Soooo naturally... it came in to my head that if I could just magically make the old brittle rubber disappear, then I would have a beautiful foundation for painting on a new layer of opaque black rubber and voila!... a like new curtain. Bottom line question, does anyone know of anything not seriously toxic that would dissolve only the rubber component of an old curtain? If so, I'm all ears.

Thanks as always,

Semi
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camz



Joined: 15 Apr 2004
Posts: 123
Location: Southern CA

PostPosted: Tue Dec 29, 2009 2:40 am    Post subject: Shutter Curtain Recoating Reply with quote

The problem with the recoating idea is that the threads running through the horizontal wrinkles become frayed and eventually fail. I've tried recoating, and the curtain usually fails right along those wrinkles.

It really depends on the condition of the curtain and how friable it is.

Have you tried plasti-dip?
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semihemi



Joined: 25 Oct 2003
Posts: 85
Location: Boston, MA

PostPosted: Tue Dec 29, 2009 3:58 am    Post subject: Reply with quote

Well, I was not envisioning just recoating. I can see a number of problems with that, regardless of the condition of the old rubber. I was thinking of stripping the old rubber first, then coating the newly uncovered fabric.

I have not tried Plasti-dip for this type of thing. My instinct would be to reach for a bombproof two-part pourable urethane with a stiff loading of carbon black pigment. Then you know that the stuff is not going to get soft or sticky under any conditions. I do not know exactly what P-dip is, or how it works, so I am not sure of its suitability for long term applications such as a shutter curtain.

Best as always,

Semi
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bertsaunders



Joined: 20 May 2001
Posts: 577
Location: Bakersfield California

PostPosted: Tue Dec 29, 2009 4:24 am    Post subject: curtain rubber Reply with quote

Semi,
Big problem with Plasti-dip....really likes to glue to itself....tried several times to use it...with curtain hanging on the clothsline in the hot summer sun....thin spray usually does not cover pinholes....enough spray to block pinholes and the roll becomes to thick to fit into the pockets....so there goes that idea! Never came up with a way to strip the old rubber off, without destroying the cloth??
That is the time when I came up with a simple way to make new curtains...well not simple...but do'able!! Will send those instructions to you if you dont allready have them!
bsaunders1@bak.rr.com
Have a nice prosperious and wellness....Happy New year.....Bert
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semihemi



Joined: 25 Oct 2003
Posts: 85
Location: Boston, MA

PostPosted: Tue Dec 29, 2009 5:38 am    Post subject: Reply with quote

Hi Bert - Thanks for checking in. Happy New Year to you too. Best for 2010 to you!

Thanks for the feedback on the P-dip. I will stay away. I think there are less risky alternatives out there, but they may need to be ordered from Grainger's as opposed to purchased at the local Mega-Mart. Regardless of the type of goop, I would think it would need to have quite a bit of black pigment added. I am guessing that around 2% by weight would be a good start. That should be pretty opaque. If not, then twice that loading should do the trick.

I have plenty of old junker curtains around by now. I feel the urge to experiment with stripping. Can you share your experiences in that area? I would like to know what did not work so that I can avoid duplicating! I am guessing that the coating on the old curtains is some form of true rubber, which may not lend itself to being dissolved by anything remotely friendly.

I would love to have a fresh copy of the instructions for making a new curtain. I switched computers a while back so I don't have all previous emails. It would be great to have the authentic Bert info right at hand! As you know I have groped my way through a few shutters but I think a good set of instructions would have saved literally days of effort.

Best to all Graflexers in 2010 and beyond!

Semi
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bertsaunders



Joined: 20 May 2001
Posts: 577
Location: Bakersfield California

PostPosted: Tue Dec 29, 2009 6:44 am    Post subject: pinholed curtain Reply with quote

Semi,
You might try black oil paint....>>artist oil paints<< use a small pointed brush, and apply directly to each pinhole! Again, to spray the paint on would make the curtain to thick to fit into the pockets! I painted a canvas for Christmas on regular oil canvis, attached it to a shade roller...I hang it in my bay window every Christmas with lights, for my display...(Bambi/Thumper/Flower and friends in front of a Christmas tree)! The curtain is rolled up every year, havent lost any paint yet, after about 20 years or so! Caution: You will need what is called "jap drier" mixed in the regular paint, so it will dry faster....or use the "acrylic" type oil paints!
Give me a jingle on email.......Bert
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camz



Joined: 15 Apr 2004
Posts: 123
Location: Southern CA

PostPosted: Tue Dec 29, 2009 4:10 pm    Post subject: Reply with quote

I've used Plasti-Dip to treat pinholes successfully. Like all media, it depends on how it is applied. Whatever coating material you choose, you must be able to roll up the curtain and place it back into the roller pocket. Thickness is crucial here.

Original curtains are coated with a material that can be dissolved with a nonpolar solvent. The trick is to find a solvent which won't leave an oily residue, or leave the coating material permanently tacky.
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semihemi



Joined: 25 Oct 2003
Posts: 85
Location: Boston, MA

PostPosted: Tue Dec 29, 2009 6:16 pm    Post subject: Reply with quote

Thanks for the feedback, Camz. Much appreciated. Do you have any particular recommendations? I think I have some toluene in the basement. I will start there unless you have any other recommendations.

Best,
Semi
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45PSS



Joined: 28 Sep 2001
Posts: 3218
Location: Mid Peninsula, Ca.

PostPosted: Tue Dec 29, 2009 8:40 pm    Post subject: Reply with quote

I have successfully used washable fabric paint to patch pinholes in bellows. I applied the paint to the inside lining of the bellows. I believe it will work on shutter curtains as well.
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semihemi



Joined: 25 Oct 2003
Posts: 85
Location: Boston, MA

PostPosted: Wed Dec 30, 2009 6:12 am    Post subject: Reply with quote

Hmmm.... very interesting preliminary test results. I dug through the shelf of nasty toxins in the basement and found a pint of a paint stripper called Strypeeze. It contains toluene, MEK and a couple of other unsavory chemicals. Sounded like just the right thing! So I painted a 3/4-inch square of an old curtain with it. The curtain had good looking fabric but the rubberized coating had all of those tiny horizontal cracks that mean only two things: the curtain won't roll up or release correctly because it can't lie flat enough, and there will be plenty of pinhole light leaks.

I applied the Strypeeze to the rubberized side of things, of course. I followed the instructions on the can: brush on in one direction and then just let it work its magic for 15 minutes. What a surprise when I came back to check the results. The rubber coating had completely lifted off the fabric! There was just a little puddle of black goo that I wiped off with a damp sponge. I then thoroughly rinsed the area with water to prevent any damage to the fabric itself. At first blush the rubber seems to have been completely removed and the fabric seems unmolested.

These are just first impressions of a preliminary result, so we don't want to read too much into it right now. One thing is clear. The Strypeeze will remove the rubber portion with no difficulty. Next step is to confirm that the fabric is OK underneath once everything dries out. If all is well, then stripping a larger area such as an entire curtain would follow. After that the challenge will be to identify a suitable recoating material. I will keep you posted.

PS: Does graflex.org have the capability of hosting photos? It would be interesting to post photos of this undertaking, but I am not sure it is possible.

Best,
Semi
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45PSS



Joined: 28 Sep 2001
Posts: 3218
Location: Mid Peninsula, Ca.

PostPosted: Wed Dec 30, 2009 9:01 am    Post subject: Reply with quote

Quote:
PS: Does graflex.org have the capability of hosting photos? It would be interesting to post photos of this undertaking, but I am not sure it is possible.


No. google (or other search engine) for free image hosting, select one of the many that are available and create an account, upload the images, use the code provided by the hosting site and post it here. I'm currently using http://imageshack.us/ which works for posting here. Use the img code to have the image show up in the post, other link(s) for thumbnail(s).

I hope you are not inhaling too much of those chemicals.
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semihemi



Joined: 25 Oct 2003
Posts: 85
Location: Boston, MA

PostPosted: Sun Jan 31, 2010 6:09 am    Post subject: Reply with quote

Well, I got 'round to a larger scale rubber stripping effort. Bottom line, there is a huge difference between stripping a spot the size of a coin and stripping a whole curtain. The process is definitely not suited to a workshop environment! It was a huge black gooey mess. I made it through half of a 5x7 curtain tonight in a couple of hours of on-again / off-again toil. In any case, the initial results show promise. After stripping I am left with a supple semi-opaque woven fabric. The stripper does not appear to have attacked the cloth. The fabric is opaque until held up against a light source. Of course I have no way to judge if the original material back in 1912 was more or less opaque before the rubber went on. My gut sense is that I did not lose too much opacity. I am toying with the idea of dyeing the curtain black as a precaution but I think it makes sense to get the carbon black into the rubber coating where it will be permanently tied down. At work I have access to raw carbon black pigment so this option is talking to me.

Also I am researching coating materials at the moment. I have narrowed my research to a couple of candidates that are likely to succeed (I think). Meantime, here are photos of the before and after stripping states. Both were taken from the same angle, same magnification, same area, same lighting, etc. Further updates to come if the recoating step step succeeds. Any suggestions for a recoating material are welcome at this stage. Plastidip get a lot of knocks but I may try a test just to be sure. Any other suggestions? Also, I am estimating that 2% carbon black by weight would be the proper loading into the rubber coating. Does anyone have any confirmation or concerns for this number?

Sorry about the weird light/dark artifacts in the photos. The curtains are of course charcoal in color.

Many thanks in advance.

Semi

PS: 45PSS, I still would prefer to have graflex.org hosting the images the way that apug.org does. It is just more comfortable.



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IanG



Joined: 04 Aug 2006
Posts: 57
Location: United Kingdom

PostPosted: Thu Feb 25, 2010 12:24 pm    Post subject: Reply with quote

So far I've repaired 2 shutters one on a pre-Anniversary Speed Graphic the other a Thornton Pickard using water soluble Acrylic black paint. This is similar to the washable Fabric paint that 45PSS mentions.

I painted it on slightly thinned & let it soak into the cloth and wiped off the excess, I coated both sides this way. The Graphic shutter curtains were flat, no creases but pinholed,

The TP curtain was very creased had a flaking coating which I had to remove first with meths, then when clean & dry I ironed it flat again, at this point the fabric was like a sieve, not remotely light proof, however the acrylic paint completely resealed the cloth, and it's fully light proof again.

Both shutters are still working fine 18 months later, there's no stickiness an earlier poster described. Now I have 3 more Thornton Pickard shutters to repair, and may make my own new curtains using the same technique to lightproof some black fabric.

Ian
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semihemi



Joined: 25 Oct 2003
Posts: 85
Location: Boston, MA

PostPosted: Fri Feb 26, 2010 1:11 am    Post subject: Reply with quote

Thanks for the information - this is really useful. Can you let us know the brand of fabric paint that you used? I would be curious to know the percent black pigment in it. Also, are the painted shutters opaque even if held up in front of a halogen lamp? I found that some of the commercially available shutter cloths look opaque when held up in front of a fluorescent or incandescent bulb, but they actually show some light pass in front of a halogen source such as a new fangled desk lamp. A good Graflex shutter shows no pass even in front of a halogen, so that is what I shoot for. However, I am not sure if such high opacity is really required.

I ended up using a 1% black pigment rubber coating. If the fabric paint has considerably more black pigment then I would be interested to try it, possibly in combination with the rubber. I only finished this past weekend so I do not know yet how smoothly the rubber coated shutter will function.

Thanks again - I look forward to your next post.

Semi
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IanG



Joined: 04 Aug 2006
Posts: 57
Location: United Kingdom

PostPosted: Fri Feb 26, 2010 12:19 pm    Post subject: Reply with quote

Sorry the paint's in the UK, and I'm not back there for 3 or 4 weeks so I can't tell you the brand etc until then, but it has a very high pigment content and so worked perfectly.

If you'd seen the cloth of the Thornton Pickard shutter you wouldn't have believed it could be re-light proofed.

I'll post the details as soon as I can, I have 3 more shutters to rebuild and will be making new cutains this way.

Ian
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