Cigarette burn in ABS Plastic Shell

[Rokumoncat]

Hi Again,

I have a NE call director that I am currently fixing up. The shell has a burn mark on the top where someone at sometime put their cigarette as it was burning, and must have forgotten about it. The scar that is left is not blackened, but rather, looks to be like a dimple where the plastic softened from the heat and sort of collapsed.

I was able to sand out the yellow mark from the nicotine, and now I am wondering about the most effective way to fix the dimple. The first thought was to take a heat gun, soften the area and push it back out. But then I realized that doing so would soften way too much plastic and that the dimple would probably become a crater.

So here is what I thought might work... First, I will take a dremel tool with a small stone burr, and rough up the dimple area. Then I will take some very small bits of moss green plastic from a smashed green phone, dissolve in toluene, and fill in the dimple. After hardening for a week or so, I will file it down smooth, sand and polish.

Does this sound reasonable?  If anyone here has any other ideas please let me know. I will not attempt to do this until I hear from the plastic experts here on the CRPF.

Thanks in advance,

R. Cat

[TelePlay]

There are a lot of techniques used to repair plastic cracks and dents at this link:

http://www.classicrotaryphones.com/forum/index.php?board=24.0

Chemical dissolution of small pieces of plastic cut from a rib inside the shell applied to the depression in several layers and then sanding it smooth seems to be the method of choice. There are some good photos of work completed showing how well that method works.

There are others so read through all the posts and see what you think is best, what you feel more comfortable with and would like to use.

[AE_Collector]

I think that you are correct, a heat gun will turn a small problem into a big problem. As TelePlay suggests, take plastic from a rib inside of the same shell rather than from a different shell.

Terry

[TelePlay]

I didn't have much time to look for this thread this morning so here it is.

http://www.classicrotaryphones.com/forum/index.php?topic=5059.0

It's one of the more comprehensive discussions of how to melt and apply plastic to a crack or gouge in the surface of a plastic phone.

As I remember, after much trial and error, Chuck decided it was better to apply more coats of thinly dissolved plastic rather than a few thicker coats. The thicker solution caused bubble to form as the solvent evaporated. The thin solution is more like layering it on so no bubbles can form under the hardening plastic. Chuck posted that discovery in another topic in this section, not in the thread linked above.

It does work. I've used this technique. As to what you use and how you do it, it's up to you. Practice on anything before working on the item to be restored. You can buy ABS many places as practice stock - gouge it, fill it and sand it down repeatedly until you get the technique down.

Good luck and post pictures, before and after.