sobota 7. listopadu 2015

Removing old or unsuccessful repairs

Repairs done by using a vinyl patch and common vinyl glue are known to be permanent. The glue is usually polyurethane filler diluted by MEK and acetone and such repairs are known to be permanent when stick together.

Even though sometimes we need to remove the patch and apply a new one. This can be due to part of the patch is starting to peel off after a few years on over exposed places because the PU glue degrades quickly or simply because we want to make the repair better.
This method can be applied on both occasions.

The main trick is to get pure MEK, Methyl eltyl ketone or butanone, cheap chemical you can buy in a model train shop or ebay.
When using a paintbrush with MEK you can start to peel off the patch with constant pouring little amount of MEK right between the patch and main material. Once the liquid MEK dilutes the closest layer of glue the patch starts to peel off with not much force needed.
After removing the whole patch you can just clean the place using ethanol or isopropylalcohol. If the remaining layer of old glue is too thick you can remove it gently by MEK too but don't expose the vinyl to MEK for too long.

MEK makes the vinyl soft and weak when touch but don't dissolves it much. When you rub vinyl with MEK you can damage the texture for example but not the whole material. So when an unwanted exposition happen just remove it gently and wait for a few hours for MEK to evaporate from the inside of the material, don't touch or rub the place until it will get the previous shape.

Warning: MEK is a pretty strong thinner so you don't need much prolonged contact with your skin until you clean it off by water..

MEK is useful chemical for other purposes also. As for model train buildings the same technique is applicable on most of those "computer's plastic" casings, for removing toner from home made pcb's etc..

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