Pink red Tubes

Cenco Megavac vacuum Pump
Cenco Megavac vacuum Pump

This problem seems to be a very a common one, so i will put in this post how i fixed the problem .
My first pink red tube started back in the 80s when i was starting on this glass bending craft, suddenly no matter how long i kept them burning in they would turn pink,actually the longer they were kept burning in the more pink they got,actually it was not pink it was a faded pink.
Well at first i tried to fix the problem myself  with no success, so i decided to call the old timers,like i used to call them back then, they were my glass bending teacher,who lived locally and my father in laws brother , who lived in Yuma Az. They both had more than 30 years in the glass bending business, actually one had been the teacher of my teacher.They both gave me the same advice ,

1.- Stop using the same glass , buy a new box of clear glass
2.-Change the oil on the pump

that was it , and it worked for a while, then another pink unit came out , out of the same batch that had been coming out ok. So now who do i call .
It took me months to figure it out but i found out the reasons that caused the red tubes to turn pink.
First i was using a very old pump and system , both built in the 40s , i was told by the old timers that everything was good , and it was to a degree.
It was a glass stopcock type of system and the pump was an old Cenco Megavac vacuum pump,which by the way i still have.
So the Findings and solutions;

1.- The problem is caused by several different things ,any of which could be present and will cause the Pink result , so that is why it was difficult to pinpoint the cause.
2.- The causes are:

a.- High humidity in the glass (caused by living in a high humidity environment , rains , leaving the glass opened to environment  .

b.- When you pump high humidity glass , all the water goes into the pump,after a while the water in the pump will make the pump not reach the appropriate vacuum.

c.-If you are using gas flasks , the problem starts when there is little  gas left in the flask and you keep on using it.

d.- You don’t have a Vacuum Gauge so you don’t know if the pump is reaching it’s appropriate vacuum

E.- Use the best quality electrodes you can find (at this moment i have been using the SVP electrodes and have had excellent results

While still using the glass stopcock system this is the solution i came up with and fixed the problem.

1.- I started to change the oil of the pump on a regular basis, once a month, especially in the winter and rain season,because of the humidity
2.- I always closed the bag the glass came in after taking the glass i was going to use , and put back into the bag the glass i didn’t use at the end of the day.
3.- I only used about 75% of the gas in the flask,and then replaced it with a new one
4.-I got a vacuum gauge
5.- I changed my pumping procedure to a two stage procedure to really take out the humidity and impurities , i start bombarding like usual and as soon as i saw a glow in the electrodes i stopped and let the vacuum pump evacuate for about 5 minutes then i started all over again and this time i went trough the whole process to the end.It takes longer but i rather spend 5 more minutes on this than having to replace the pink unit once it’s been installed.

The best results with the least of problems is when i bought the O ring vacuum system with gas tanks , and a new vacuum pump (Welch 4202 belt driven)with a diffusion pump, i still do the two stage bombarding .
Now my red units come out bright red all the time , haven’t had a pink one since 1990, and a red unit only takes half a second to come to full brilliance when i put it to burn in , when the unit is larger than 12 feet it takes one to two seconds , i still leave them at the burn in table for about ten minutes with a 15000 60 ma transformer.
I have also noticed that when a repair comes in that was red , 90 % of the time if i use the same glass , the red does not come out good, especially if it was a channel letter neon and it was broken and stuff got onside it , i  just don’t waste time trying to reuse the glass in a repair i just make it new and know it will not come back

Well hope this helps all the glass benders that are still out there , don’t give up, if you are out of work and still want to keep on bending glass , i will put on a future post all the different ways to still make money from bending glass , please stay tuned , and e mail me to if you have any questions.