Monday, April 17, 2017

Masking: The Problem

Spring fitting out season is approaching (or is already here for those of you south of the 48th parallel).  That means that there will be painting and varnishing, and where these exist, masking tape is not far behind.  There are all kinds of the stuff out there, and believe me, they are NOT equal, or even close.  Please allow me to give you the benefit of 20 years experience fitting out Eolian, and even longer in masking cars for painting...

Just: No.
There are all kinds of masking tape at the bottom of the rung, cost-wise.  For almost all uses that we here care about, they should be avoided.  The denizens of this rung of the masking ladder, even from a respected manufacturer,  have an inferior backing (that is, they will frequently tear lengthwise wihen you are attempting to pull a piece off the roll...), have an adhesive that is set by the sun, and are worse than useless should they be exposed to moisture (such as dew, on a summer's morning).  If you can get a good piece off the roll, in a day or two in the sun and morning dew, it will be permanently bonded.  You'll need solvents to get it off.  Even for painting a car, where the masking is applied and removed in the same day, the bottom tier is simply not worth it.

Probably No.

The next tier up is useful for things that will be applied and removed in a single day, or where the tape is shaded and protected from moisture (inside perhaps?).  When painting cars, this is what I use to hold the newspaper on the windows, etc.  But not where a clean line is needed.  You probably won't want this anywhere on a boat either.

Scotch's blue "painter's tape" is one that you might consider.  But it has what I consider an overly-aggressive adhesive (it might pull off an underlying paint layer), and also has a tendency to set up in sun or rain.  In addition, like the other tapes mentioned above, it has a "crepe" backing.  That is, the backing is slightly wrinkled on purpose, to make it possible to bend the tape around a curve.  Tho this could be handy in some cases, the wrinkles allow the paint to seep under the edges like this:

... so don't use this where you need a clean edge.

The only tape you'll find aboard Eolian is this:

Yes: Scotch 2080

Scotch 2080 (note the orange core).  This tape has,
  • A smooth backing, making for nice clean edges
  • A less aggressive (but perfectly acceptable) adhesive.  In most cases, it won't lift underlying paint layers.
  • An 8-day removal period.  Well, this might be slightly exaggerated, but still, under most circumstances, you won't need a chisel and acetone to get it off.

And a final note:   You use masking tape to prevent getting paint on the substrate.  This means almost by definition that you will be painting over the edge of the masking tape.  When you pull the tape, depending on how heavy the layer of paint is, how strong the paint is, and how well it is cured, you could pull chips or entire areas of paint off into the painted area.  To avoid this, I never allow more than one cured layer of paint on the tape before it is removed.  For example, when varnishing I pull the tape before the second coat has had a chance to set up hard.  This may be a little more work, but it avoids having to use a knife to cut the paint layer (and thus probably scoring the substrate) when pulling the tape.



PacificSailors said...

Great advice Bob! Very timely. What are your thoughts on the green painters tape? Thanks!

Robert Salnick said...

Are you referring to the "Frog tape"? Haven't tried it. Is that what you use?

PacificSailors said...

A house painter friend of mine swears by frog tape. I will buy some of the blue tape you suggest and some of the green tape. I will let you know. About to start our spring time fun, too!

Robert Salnick said...

Great! I'll be anxious to hear your report!

Rick said...

Great post, Bob. Now that I've​ already struggled with tape this year, the lesson is learned - again. I won't skimp on tape again. Just not worth it.

dbostrom said...

Yeah! And certain stretchy types of goo (silicon caulk around toilets, for instance) -really- need the tape pulled off within a few minutes, or the line will be spoiled as the material lashes back.

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