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It seems that the patches I buy for fixing inner tubes come in one of 2 types. Both have metal foil on the stick-to-tube side. One has paper on the other side, the other plastic.

With the paper ones I can peel off the foil, glue them down, wait a minute, then split the paper from the centre and tear it off.

I can't do this with the plastic backing - any attempt to remove it seems to lift the edges.

Am I supposed to leave the plastic on, remove it before I glue the patch, or what?

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It's a question I've asked myself! I don't know the answer, but I always leave the plastic on, and have had no problems! –  Darren Cope Nov 27 '10 at 0:21
    
are you talking about a patch for the tube or for the tire? (I've heard the ones for tires called a "boot".) –  Neil Fein Nov 27 '10 at 19:07
    
Edited to clarify –  Duncan McGregor Nov 27 '10 at 20:49
    
I leave the backing on, to prevent the tube from sticking to the inside of the tire. If it accidentally comes off I apply talc or roadside dust to the patch area to prevent sticking. –  Daniel R Hicks May 7 at 11:21

3 Answers 3

up vote 3 down vote accepted

The Rema Tip-Top patches that I use--which sound similar to those which the questioner describes--come with instructions in each plastic box. The package that I have shows the instructions pictorally in seven steps.

Here is the product that I use: http://www.artscyclery.com/descpage-79002.html

In step 7, the manufacturer distinctly recommends that the user remove the plastic backing.

I usually remove this cellophane backing myself. It sometimes is a little finnicky--if your patch isn't totally set it will seem to pull up the patch. Just use your thumb to set the patch more carefully. In the package's Step 6, the manufacturer uses a totally unidentifiable rectagular object to smooth out the patch before removing the cellophane. I use my thumb, personally, and it works just fine.

If one side of the cellophane won't seem to come off without removing the patch, you didn't put down enough vulcanizing fluid. Try the other side. If the patch is reasonably centered, this shouldn't be a problem.

The answer about leaching chemicals is news to me--though I admit freely that I never looked farther than the instructions in the box for advice.

Once in a moment of frustration, I left the cellophane on and put it into the tire--no problems so far. I had some concern there would be a problem if the cellophane were stuck between the rim and the bead but this doesn't seem to have been a problem for Anthony K or Darren Cope.

It looks as though it doesn't matter, but the manufacturer of Rema patches recommends removing it. I say remove it carefully. This is best done if you are generous with the vulcanizing fluid and careful to press the patch into place.

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Thanks for the excellent reference - I've now accepted 2 answers, and am trialling leaving the plastic on to see if it causes any problems. I'll report back if it does. –  Duncan McGregor Dec 4 '10 at 0:01

I followed the advice of leaving the plastic film on. After a few days the tire went flat again. Inspection revealed that the tube was puckered around the patch because the plastic film does not stretch in the same way as the tube and the patch. The new leak was coming from under the patch. Therefore from now on I am going to try to take the plastic off.

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I've never seen this behavior, and have difficulty imagining it happening with the style of patches I use (Park or Rema, generally), since the plastic film is so lightweight. (I'm trusting that you put the patch on right way up?) –  Daniel R Hicks Jul 6 at 20:36

You should leave the plastic backing on, and the paper ones as well. The backing stops chemicals from the patch and glue working their way into the tire at the location directly in contact with the patch. I do not know if this leaching weakens the tire at all, but in many cases it will cause a dark "patch" to appear on the tire sidewall after an amount of time, which can look unsightly. After a long period of time (months) the plastic and paper will disintegrate by themselves so you don't have to worry about removing them.

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I have tried leaving the plastic backing on, but worried that it would prevent the patch from expanding enough with the tube. Plus when I fold the tube to store it, I've wondered if the plastic would pull the patch off (I'm very conservative when it comes to fixing tubes - don't want to replace one puncture with another;-) Has anyone had any problem leaving the film on? –  Duncan McGregor Nov 27 '10 at 16:46

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