How To Cover Your Model With Tissue
Before we start, please be aware that this is a guide for beginners.
Yes we know there are about 250 different ways to cover your balsawood model using all kinds of different tissue, applied wet or dry, doped or not, trimmed with a blade or using sandpaper, hindered or helped by listening to a live Derby County match on the wireless, etc, etc.
Andrew Darby, designer of our Magnificent Flying Machines range, has kindly taken time to put together this step by step guide for beginners using the tissue included in our kits. (Thanks also go to Darby Jr for holding the camera!).
Take it away Andrew...
COVERING THE FRAME WITH TISSUE
The VMC kits are made from a balsa wood framework with a tissue “skin”.
Applying this skin can be a bit tricky at first but with a few simple tips and hints and with the aid of these photographs, it is a skill that is easily learned.
As with many things there are lots of ways to achieve the same results, but this is my preferred method and the one shown in the kit instructions.
1 - First make sure that you have properly sanded the tail plane using the fine sandpaper - both on the surface and at the edges so that they are smooth and free from lumps and bumps.
Take care to be gentle and do not press to hard or sand one particular area otherwise you could create steps or make the part too thin.
2 - Mix some of the PVA with some water, anywhere between 70% PVA to 30% water to around 50% of each should be fine.
3 - Carefully cut out two pieces of tissue that are big enough to cover the part.
The longest edge of the pieces should be along the longest edge of the tissue sheet.
Leave a border around the part. You need not be too precise, but don’t waste too much tissue to ensure that you have enough for the rest of the model.
4 - Lie one of the tissue pieces flat on your board, then apply a thin layer of glue using the glue stick to one face of the outside of the framework only.
Use the “sharp” edge of the glue stick, rather than the flat face of it. This is much more precise and stops the glue being pared off in lumps by the ribs and adjacent parts.
I normally do two light “circuits” of the frame - this makes sure everything is coated while ensuring there are no lumps and bumps of glue.
The following clip shows this technique in action:
NB The clip shows one side already covered as that is when I did the video, but the same technique applies.
5 - Carefully put the frame down onto the tissue on the bench, then turn it over and tease it out with your thumbs and run your finger round the edges.
You do not have to make it tight - in fact do not try to stretch it too tight.
6 - Turn the part over and cut the tissue away leaving a border of around 1mm or a little more all the way around. The first picture shows this around halfway through and the second picture all done.
The idea is to provide an overlap that can be rolled over and stuck to the edges of the part.
7 - Now apply a “bead” of the PVA mix to the edges of the tissue and in small stages roll the tissue up to meet the edges of the part.
Run your finger carefully around the edge. NB Try not to get the PVA on any other part of the tissue or it may affect the way it will shrink tight later.
This little video clip demonstrates this technique:
8 - Allow the PVA to go off for 15 minutes or so (I normally start covering another part while I am waiting) and then repeat for the other side allowing the same tissue overlaps, etc.
9 - Now the part is fully covered, leave it for 24 hours to allow the glue to set fully before water shrinking the tissue.
WATER SHRINKING THE TISSUE
As described in your kit instructions, the tissue covering is “water shrunk” - that is, by carefully wetting the tissue, it will contract and go tight over the structure.
The key things here are to apply a light mist of water and then hold the part flat until the tissue is fully dry. Not holding it flat may result the part twisting or warping.
For this model I am using traditional cellulose dope or a variety of it called Banana oil. This seals the tissue and prevents any more shrinkage and thus the potential for warps.
Your kit instructions state that there are other alternatives to cellulose dope and these include acrylic-based sealants such as Eze Dope.
If you go the traditional dope route or plan to use a spray on lacquer or sealant, then use plain water to shrink the tissue.
If you are using Eze Dope, then use a 5% solution of Eze Dope and water to shrink the tissue instead of plain water - this gives the tissue the required wet strength for the final coats of Ezedope later on.
1 - First make some spacers using some of the scrap edges of your laser cut balsa parts sheets.
Use scrap from the same sheet if possible to ensure that the spacers are approximately the same thickness.
The spacers allow the part to be held flat while allowing air to circulate underneath it.
The tissue covered part can then dry properly without sticking to the board.
2 - To make the spacers, lay down a strip of scrap balsa and cover the top side in sellotape or similar sticky tape (this will prevent the spacers sticking to the part).
Cut away the excess tape each side.
Now cut the strip into 20mm long lengths as per the kit instructions.
Make a good number of spacers so that you have plenty to work with.
3 - To deliver the water spray, use an old perfume atomiser or similar – anything that can deliver a fine mist of water is perfect.
The one in the picture is one of three that I bought on eBay for a few pounds.
4 - Wet the tissue each side - a gentle mist is all that is required. DO NOT SOAK THE PART.
Now place the part onto the spacers at the edges only.
At each spacer, either use pins set at an angle or use small weights to hold the part down.
In the picture I have used some small paint pots to act as weights. I have left the yellow pot out of position so that you can clearly see the spacer at the edge.
5 - In the next picture you will see that the tissue is partially dry.
Where the water has evaporated, the tissue is taught - it is slack where it is still wet.
Don’t move the part for a while - an hour is advisable at normal room temperature.
Note that even when it looks dry on the top, the tissue on the underside can still be wet as it takes longer to dry there.
6 - This is the part fully dry.
The tissue should be nice and tight and the part still flat.
The following clip shows the fully dried and flat covered part.
7 - Now you can apply dope or lacquer to the tissue and clamp or pin down as before to hold the part flat until dry.
NB If you are using Eze Dope, use a nice soft brush and be gentle with it. Also make sure you brush it out properly to avoid patchiness on the tissue.
Well folks, that's it!
A huge thanks to the Darbys for what we think (humbly) is the best covering guide for beginners on the web (having said that, there is a great guide showing how Mike Stuart does it here).
We hope this helps you tackle your first model and we'd love to get your feedback, so comment away below...