I use these:

https://proofflyfishing.com/collections ... r-stoppers

Try taping the male for masking purpose with string under tape to hang by and any available plug to stopper the female?
I've never dipped rods but was thinking of it a few weeks ago and was intending to taper a dowel as a plug, since wood is my go to material. If using a sold plug like Matt's I think a piece of wire through the center and looped would be handy.

For butt sections I always tape off the ferrule section (when needed),plug the female ferrules and dip away. Sometimes its nice to dip just the first 1/4"-1/2" of the grip into the spar and then a nice slow extraction. For tip sections I usually dip it tip down and then install the tip top after the varnish has cured for a few days. You can lightly remove the varnish from the tip 3/8" or so from the tip to make sure the epoxy/glue has a clean surface to bond to.

Hello
Respectfully disagree.
GOOD QUESTION !!
So called modern fiberglass rods, I wouldn't be qualified to answer for,I'm a Classic Glass kinda guy.Dip No Dip I Could Care Less whatever blows your skirt up.
For me I evaluate the finish of the blank,only can I then decide if the blank will benefit from Clear Coat with U.V. Protection.

Classic Glass Blanks Or Rebuild Remake Projects I'd say that a U.V. Protrective Clear Coat Is Always A Very Good Idea.

Now to the question;
When dipping a Fiberglass Or Graphite Blank With Glass Or Graphite Ferrules,Be That a Tip or Mid what ever the case may be, usually use a short section of rod blank inside the female ferrule to suspend the tip/section from during the dipping process.To Plug Metal Ferrule Ends Or Glass Or Graphite Blank Ends I often use Either Cork Or Rubber Stoppers.

You can purchase These stoppers at any hardware store for a few Penney's,The last time I purchased any had to be 10 years ago they are reusable.

Have some of the Corks Vince Cummings Made For His Dip Plugs,Vince Threaded Copper Wire Through The Cork and Made a Loop To Hang His Blank Sections From Nails In The Shed By The Plugs.
Tape Yes I also use masking tape and use the tape at times to seal ferrule spigots, ends, etc, etc as needed.
No wrong way to do this what works for you is best.

Most Factory Glass Rods were dipped the same way they dipped baseball bats,in and out of the dip so fast if you blinked you would miss it,that's why the wraps on the cheap cheap rods had so little finish on them.

I'm in the process of Refinishing Some of my classic Worlds Finest Phillipson Blanks over in the what's on your bench topic.

We had a close family friend pass away recently so I've been attending to his Family out of respect & Old Friends in town n all.

I'm trying to get back to my projects this afternoon,I'll get some pictures of how simply I sealed my ferrules prior to my blank refinishing process.

Usually hand rub the finish on most of my Bamboo Rod Projects

Tight Lines And Whatever Blows Your Skirt Up Loops
Andy M