Paint for silicone rubber ("Silastic") rollers in Graflex RH-50 back

[LF_rookie_to_be]

So I decided to paint the light-coloured rubber rollers in my RH-50 black, matte black. In order to reduce reflections after the window in the shell has been widened to 12 cm (to get a 6x12 back). The reflections may easily appear when making long exposures on AURA film with no anti-halo layer. What type of paint should I use?

[Jim C.]

I don't have one of those backs, but looking at pics of them I doubt that the rollers are silicone rubber,
some look to be gum rubber ( amber ) not so sure about the white ones I see, very odd to see such
a large light colored part inside a film magazine.
If they were silicone they would be difficult if not impossible to get the paint to cure and stick
since the rollers would be a heat cure variety of silicone.

If you're willing to test it , nick a tiny chip of of the roller material and use a lighter to burn it
if the odor smells sulfury like a struck match then it's a gum/ neoprene type rubber,
silicone will not have a sulfur odor.

[LF_rookie_to_be]

Since there seem to be several iterations of this back, here are a few pics of one of the shells. Both of the two backs I have are branded "General Precision", so not the latest, "Singer" branded type. One came with the manual which expressly mentions "Silastic" as the material for the rollers.

http://i40.tinypic.com/b63si9.jpg

http://i39.tinypic.com/34pm5y0.jpg

http://i44.tinypic.com/29sec0.jpg

http://i44.tinypic.com/xnahq9.jpg

[Jim C.]

Interesting....Silastic is a trademark for Dow Corning silicones, I haven't used those in eons.
You can try contacting Dow Corning and see if they have a compatible paint.
They're probably going to say you'll need some sort of 'etching' primer before painting, not related to
photography but silicone props I make I usually wipe down with naptha or lacquer thinner to
clean the surface and open the silicone pores to grab the paint.

Those rollers need some serious cleaning, and confirms my observation that silicone rubber is a dirt magnet :)

[LF_rookie_to_be]

Reply from Dow Corning:

"Thank you for this request to Dow Corning and sorry for the late response as i was out of office.

Concerning your request, you need to know that Dow Corning is no paint manufacturer. We however offer silicone resins and additves for paints, inks, lacques etc, If the roller is made of silicone, it would be difficult to adhere to the surface. Normal organic based paints may not adhere to the surface of the rollers. An option here is using an acetoxy curing sealant (gives off acetic acid while curing) that has better adhesion to silicone substrates but it is important to consider the consequences of using an acetoxy cure adhesive around electronics or sensitive materials. We normally do not propose such acetoxy systems for use on electronic parts. So it is your decision to evaluate on such equipment like yours.

You could test Dow Corning 732 sealant or the more flowable version, Dow Corning 734 sealant. More informatin on these sealnts can be downloaded from our website: www.xiameter.com"

[ic-racer]

You can't paint silicone. How about trying different film or try wrapping them with black electrician's tape.

[el french]

You could also cast new rollers with silicone or urethane in any color you like. I was really amazed how easy it is to do.
Here's a couple of videos:
http://alumilite.com/ProdDetail.cfm?Category=Silicone Rubber&Name=QuickSet
http://alumilite.com/ProdDetail.cfm?Category=Casting Resins&Name=Alumilite Regular