After doing my Instructable on making a model building board I could not help whipping out one of my kits and putting it together. In this case it is the Guillows Lancer. Being that this is a small rubber band powered model that needs to be light to fly correctly there are only a few options for covering the model. One you could cover it with a plastic film like Nelson Lite film or even colored plastic wrap, or you can cover it with good old fashioned tissue. I decided to cover mine in tissue as it is cheap and does not require any special tools or materials. This type of model is often referred to as a stick and tissue model, so it fits.
Back in the day one would attach tissue to a model with model dope and then shrink it with water. I have used dope in the past and it is nasty stuff, it smells bad and I'm sure the correlation with the drug is quite fitting. So instead I am going to show you how to attach the tissue using glue sticks and use alcohol to shrink it. This method is not only less toxic then using dope it is also cheaper then dope and it is quicker in my opinion.
Step 1: Materials
To cover your model you well need:
- A model, this should be self evident.
-Tissue, I use ordinary craft tissue, also called "Domestic Tissue" because a lot of people swear by Japanese Tissue, just make sure it is the none bleeding kind and also that one side is shinny and the other is dull in appearance for some reason it seems to make it work better.
-UHU Purple glue stick, some people use Elmers or Scotch purple glue sticks but the UHU is the tried and true one to use.
-Rubbing alcohol, used to shrink the tissue after it is attached to the frame.
-Spray bottle, used to spray the alcohol on to the tissue with.
-Razor blade for trimming the tissue.
-Sand paper to sand the model before covering and to trim the tissue with.
-Krylon "Crystal Clear" spray paint to seal the tissue.
Step 2: Preperation
To begin you need to prep the model for covering. Use a sanding block with 220 grit sand paper, smooth out all of the surfaces of the model that well contact the covering. Remove glue build up and any bits of wax paper that might have stuck to the model when building it.
Also you well need to determine which way the grain of your tissue is going. To do this you simply tear the corner of the sheet of tissue in both directions. The tissue well tear cleanly in the direction of the grain, usually length wise. This is important because the tissue well shrink perpendicularly to the grain and if the grain is not going the right direction on curved surfaces you well never be able to remove all of the wrinkles.
Step 3: Applying Covering
The process of covering is actually pretty simple.
- Start by spreading your tissue out on a flat smooth surface and lay the part of the model to be covered on the tissue with its length parallel to the grain of the tissue. Using a razor blade cut a piece of tissue out about 1/2" or more larger then the section to be covered, just cutting a rough box around the part works well. Do not try to go around a corner of a model, on the fuselage cover the bottom then the sides and finally the top with separate pieces of tissue.
- Next apply glue to the the section of the model where you want to attach tissue to, for larger panels it would be better to work in smaller sections to make it easier to handle.
- Now carefully lay your tissue on the model and gently press the tissue onto the frame as you carefully pull on the tissue to remove as many wrinkles as possible, it is easier to smooth out the wrinkles if they are small to start with. If the glue begins to dry before the tissue is completely attached you can take a Q-tip with some rubbing alcohol on it and swab over the tissue in that section to reactivate the glue, be careful not to pull hard on the tissue when it is wet as it well be soft and tears easily.
- On wings it is best to cover them in sections, this helps reduce the number of wrinkles in the covering especially on the top curved surface of the wing.
- Wait about 10 or 15 minutes for the glue to completely harden and take your sanding block and gently run it along the edge of where you just covered to trim off the excess tissue. If you sand to hard it well sand into the wood and might not be good. You can also use a razor blade to trim the tissue off as well.
Step 4: Shrinking the Tissue
- Begin by filling the spray bottle with half and half rubbing alcohol and water, too much alcohol well cause the glue to soften and the tissue well come lose and not shrink properly.
- Set the spray bottle to generate a fine mist of alcohol.
- Spray the surface to be shrunk, on wings with dihedral shrink one section at a time and shrink both the top and bottom of the wing at the same time.
- On flying surfaces, wings and tail, to keep them from warping set them on the building board and pin them flat and let the tissue dry before removing it.
- If there is a section of covering where a wrinkle did not stretch out you can respray the model again to shrink it even further. You can also spray it with strait water which shrinks the tissue more but can also warp the surface more if it is not pinned down well. If that does not work you might have to recover that section.
Step 5: Finishing
Once everything is dried you can remove the parts from the building board and spray them with a light coat Krylon Crystal Clear acrylic spray. This seals the tissue preventing moisture from wrinkling the tissue and warping the flying surfaces from changes in humidity. Then just assemble the model as explained in the directions.
Step 6: Repairs
If for some reason you get a hole or tear in the covering you can repair it quite easily.
If the hole or tear is small, tear off a piece of tissue from your scrap and apply glue to the dull side of the patch. Stick the patch piece over the tear and gently smooth it out with your finger. After the glue has dried spay it with alcohol and it well shrink smooth. Note: to get a smoother patch tear the edges of the patch this leave a less noticeable edge when it is glued to the rest of the tissue.
If the hole is large it is best to carefully cut the section out to the surrounding balsa frame and make a patch to cover the whole section, sorry no pics on this one maybe after I fly it a couple of times.
After the tissue is done shrinking you can respray the area with clear to get it to match the rest of the tissue.
apprenticeS made it!