Film-Tech Forum ARCHIVE: PTR melted into projector

This is topic PTR melted into projector - best cleaning agent? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=011589

Posted by Jock Blakley (Member # 6552) on 01-16-2014, 07:03 AM:

Melbourne's been enjoying some "rather warm" days recently - beyond 40 C / 105 F for the last four days - but today was particularly foul.

We only run shows at night so the box isn't climate-controlled during the day... and it seems that today it was hot enough to melt the one (disused) PTR that had been left on the No 2 machine.

It's melted down into the head, as you can see below:

Would anybody be able to recommend the best cleaning agent to shift this gunk without damaging anything?

Thanks.

Posted by Edgar Prass (Member # 7558) on 01-16-2014, 07:55 AM:

PTR's are coated with urethane, which is soluble in the cheapest solvant available - water. Warm water is better solvant than cold water. If water on some strange reason doesn't solve it well enough try clean denatured alcohol, benzene or ether. Beware that all are flammable and moderately toxic compounds.

Posted by Louis Bornwasser (Member # 3063) on 01-16-2014, 03:23 PM:

Remove parts and soak in water over the off season. Try more and more volatile solvents until bad stuff (and paint) are gone.

Bead blasting??? Louis

Posted by Marcel Birgelen (Member # 6801) on 01-16-2014, 04:43 PM:

That looks kind of vicious...

I didn't even know that PTRs can actually melt at "normal" temperatures.

Maybe I'm missing something, but I've never actually understood the benefits of those things anyway. You're transferring dust and particles to those rollers only to hope they stick there long enough not to be picked up by another part of the film.

Posted by Jock Blakley (Member # 6552) on 01-16-2014, 08:34 PM:

Cheers Edgar and Louis. I'll give that all a go during the DLP show tonight.

(no off-season here, just a few days of digital shows before the next scheduled 35mm show)

Marcel: I'm pretty sure the temperature in the box yesterday was anything except "normal"! It was >45 C outside during the day so I reckon in a sealed-up brick room against the outer wall of a brick building it could have climbed past 50 C with no trouble.

The rollers haven't been used in years because, as you say, they are pointless. Just didn't occur to anybody that they should come off the machine, especially since we use the guide roller at the front of the PTR unit to run film from the feed reel to the DTS reader.

Happily, since the PTRs that were being used as paperweights also melted, this is only going to be a one-time problem [Razz]