How do you mask diagonal corners?

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BMcD

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On a rocket like an Estes V-2, there are spots on the body tube where two corners need to meet. For example, once the yellow base coat is applied, I need to paint the black checkerboard design as a top coat.

To do that I need really precise rectangles of tape on the body tube that exactly cover the areas that will be yellow blocks on the finished product.

To get good straight lines and avoid bleeding, I normally let the masking tape extend a bit beyond my corners. But in a spot where two corners meet, I would need to very precisely mask off the portions that will be base coat, and have a very precise corner left exposed for the top coat. How do you guys get really good lines at those corners? Do you do two different rounds of masking and painting the top coat? Or do you trim the tape with a hobby knife once it is applied? Or some other technique I have not thought of?

TIA.
 

Zeus-cat

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If you want precision corners you need to put the regular masking tape away. You want to use vinyl masking tape. Tamiya makes it in various sizes such as 1 to 5mm.

Vinyl tape is much easier to use with curves as it is fairly narrow and lays down nicely on most surfaces. It burnishes much better than regular masking tape as well. It also stretches a little if you cut it just a little short.

For corners I cut one end of the tape at 90 degrees. The other end is cut at 45 degrees or so (the exact angle is not important). In the diagram the first two piece of tape have been applied. See how piece #2 is over #1. and if its not quite lined up I can trim just a little corner to get it to fit just right instead of having to cut the entire width of the tape. Just make sure you burnish the tape where it overlaps. The middle can be filled in with masking tape.


Tamiya masking tape.png
 

BABAR

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If you want precision corners you need to put the regular masking tape away. You want to use vinyl masking tape. Tamiya makes it in various sizes such as 1 to 5mm.

Vinyl tape is much easier to use with curves as it is fairly narrow and lays down nicely on most surfaces. It burnishes much better than regular masking tape as well. It also stretches a little if you cut it just a little short.

For corners I cut one end of the tape at 90 degrees. The other end is cut at 45 degrees or so (the exact angle is not important). In the diagram the first two piece of tape have been applied. See how piece #2 is over #1. and if its not quite lined up I can trim just a little corner to get it to fit just right instead of having to cut the entire width of the tape. Just make sure you burnish the tape where it overlaps. The middle can be filled in with masking tape.


View attachment 463102
Just out of curiousity, other than cost and thinner sizes, what makes Tamiya tape different from electrical vinyl tape?
 

heada

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I just masked a 3" BBX and the lower section has opposing corners. just like you're facing. I used 18mm wide Tamiya Masking tape to do it.



I used it because it's thinner than standard painters masking tape. It lays down better and seals to the base paint better and is ever so slightly translucent so I can see if it has sealed to the base paint better. I use it as the outline and then fill the center with cheap 3M painter's masking tape. (3M releases best I've found) I also have 10mm version of the same that I use on smaller rockets or if I need to do curves. Fill and sand, prime, base gloss white, base color, mask, next color, pull masking, mask for next color, etc. Having the base gloss white or a base color to mask onto helps with getting a good seal so you don't get bleed under.

Electrical vinyl tape is much thicker, and doesn't release nearly as well. I'd never use it for masking.
 

Antares JS

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Another thing you can do that worked for a similar paint pattern on my Estes Doorknob, is to do only one ring of rectangles at a time, starting at the top or bottom and working your way to the other end. I sprayed my whole Doorknob white, and then masked and painted the two orange stripes on the nose, waited a week for it to be completely dry, and then masked and painted the orange stripes on the body. No precise cutting of masking tape ends required.
 

mjennings

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I did something very similar to what @Antares JS describes on my Estes Maxi V2 years ago. White base then a couple of different mask to get all the black done.
 

Jay Rairigh

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I do the opposite of Zeus-cat. I will mask the outside of the square with 4 pieces of tape and paint the inside of it.
This way I don't have to 'build' a square overlapping corner with tape but just lay down 4 straight lines and let them overlap as much as I care to. Of course, I burnish the corners down, usually with an exact-o blade.
 
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