opaque plastic "caulking" for holgamod?

davido · Feb 17, 2014

I've been working on a fairly intense Holga modification. Up until now, I've been using black electrical tape to seal cracks ect. But I really would like find a more permanent solution: some sort of totally opaque black plastic sealant. Almost like plastic caulking which would be thick enough to fill cracks, like a thick black resin? I was looking at something like this:
http://www.amazon.ca/Permatex-80338-Black-Rubber-Sealant/dp/B000HBM37A but I'm not sure if it would be thick enough?

Newt_on_Swings · Feb 17, 2014

Any plastic epoxy that can be tinted or pretinted black should work. Make sure it is formulated for plastic or it can melt what your tying to put together.

jp498 · Feb 17, 2014

Also consider "liquid electrical tape". Haven't tried either on cameras.

My Holga doesn't leak at at..

DWThomas · Feb 17, 2014

If it's to be more or less contained within a joint, there are automotive weatherstrip cements that are black, albeit pretty sticky and messy.

Truzi · Feb 17, 2014

The first thing that comes to mind is RTV silicone. However, I don't know how light-proof it is, and it can smell bad and appears to off-gas for some time. I don't know if it would be good when film is nearby. Also bead-seal for tires (same caveats as RTV silicone).

shutterfinger · Feb 17, 2014

The sealant you linked to is commonly called RTV sealant. It dries solid but has a rubbery feel. There are many black silicone rubber sealants in the RTV family.
Plasti Dip http://www.homedepot.com/p/Performix-Brand-Plasti-Dip-11603-6/202196703 is similar to silicone rubber. The can dries out relatively quickly, a few weeks, once open. Contains toxic chemicals VM&P Naphtha, Hexane, Toluene, Methyl Ethyl Ketone, msds: http://www.plastidip.com/docs/Plasti Dip 14.5 oz MSDS.pdf . Dries like the coating on tool handles.

One of these calks: http://www.homedepot.com/s/black%20calk?NCNI-5
Paintable or tintable epoxy.

Truzi · Feb 17, 2014

Oh, something about RTV. It seems to come off easily (at least in automotive situations). It is not permanent in case you make a mistake or otherwise want to reverse it.

Fixcinater · Feb 17, 2014

I've sealed up some bellows on weird old folders with liquid electrical tape. It's cheap and sets up fairly quickly. Quite runny when it's still liquid so you have to be careful and modest when applying, leading to multiple applications for full light-tightness.

Dan Daniel · Feb 18, 2014

You can dissolve acrylic in solvent. #4 acrylic solvent is best for this. Clean your saw or sander, then generate a bunch of ground black acrylic. Put the dust/flakes in a glass jar, then add #4 to form a paste. Now brush this into your cracks. It may take time to build up enough to fill a larger crack.

AgX · Feb 18, 2014

I would use epoxy glue. Coloured with special black epoxy-colouring-paste (dye/pigment in epoxy-resin).

Thus you would substitute a part of the original resin by that coloured resin. Make a test sample in advance. Be aware that the colouring might not be IR-proof.

You might make colouring paste yourself by adding carbon-pigment to your resin.

cramej · Feb 18, 2014

I've used Marine epoxy with good results. It is opaque dark gray when mixed, though you need to make sure the kind you get has a white tube and a black tube. It worked well enough to make a reliable tripod mount with a 1/4-20 nut in the bottom of the camera and mount a Dories (diana clone) lens and shutter on another Holga.

davido · Feb 20, 2014

Thanks to everyone for your replies!
I have found a product called Kwik Plastik from JB Weld. It's a plastic repair epoxy putty stick. I'm hoping this will be the thing, as it't the consistency of putty and therefore easy to work into corners and cracks. It's dries grey but can be painted. I'll give it a try on the weekend and let you know how it works.
david

opaque plastic "caulking" for holgamod?

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