Today I tediously soldered a 16-way ribbon cable to veroboard at one end and a DB-25 socket at the other end. Because I was manually stripping the wires and so on, it's possible that if either end is jiggled about, some wires might accidentally be crossed. It's also possible that if I give it a good yank, one or more connections might get ripped out.
May I suggest that a good place to start would be to improve your soldering and wire stripping technique, rather than just covering it in sticky stuff.
When you have separated the strands of the ribbon cable, consider where each strand will connect on the DB25.
Maybe that some strands need to be longer than others to get a good "lay" to the strands rather than just a jumble.
Sometimes the best that you can do is still a jumble, but at least aim for something which is tidy.
When stripping the insulation from the wires, consider how much wire will go into the solder bucket on the connector pin.
You only need to strip about 3mm of insulation.
When the insulation is stripped, gently twist the strands of wire so that they lay together and then tin the exposed strands.
Dont use too much solder and make sure that the soldering iron is not so hot that it melts and burns the insulation.
About the connector.
Make sure that the connector is held firmly so that it is not skating around the workbench as you try to solder.
Use a small vise to hold the connector.
Not got a vise?
Try using a blob of BluTack, in the past I have used an adjustable spanner as an impromptu vise.
On the connector, fill each solder bucket with solder.
Not so much that the solder forms a bulging blob, just enough that there is a concave meniscus to the solder surface inside the solder bucket.
Now we are ready to solder the wires into the solder buckets.
Ensure that the iron is clean and has a small amount of solder on the tip,
touch the iron on the side of the solder bucket to melt the solder inside and insert the wire up to the insulation.
Remove the soldering iron from the pin and hold the wire steady whilst the solder solidifies.
Repeat for each wire and voila! you have a nice tidy connector which does not need to be daubed with anything.
JimB