Originally Posted by bunkai
great covering job! It's another daunting aspect of this project for me. Could use some tips when the time comes. Like how you could cleanly get the red/white and black in there to look like it was painted on. Great job!
I use Monokote primarily. Not that it is any better than some of the others, but I have used it for over 20 years and know how to work it, so hard to change. Can't believe at 44 that I am getting set in my ways. Can hardly wait to see what I will be like in a few more. Might have to stock up on MonoKote just in case they discontinue it! LOL. You can apply the same techniques to pretty much any film covering, but you will need to consider the temperatures it will work at as they are all different. The most popular and readily available two films seem to be Monokote and Ultracote. Monokote requires a much higher temperature, and Ultracote may be a little friendlier to work with in some respects. MonoKote has matching paint for a good number of the colours. Any other film that I am aware of for the most part you will need to get paint mixed to get a colour match.
To start – ensure you have a good finish on the model. Covering, just like paint, will not mask imperfections, so try to get the best finish you can by sanding and filling and more sanding. Make sure the surface is cleaned up from any dust or particles before you start covering.
Tools to consider are:
- Small trim iron like a Top Flite or Coverite. I use both. The TopFlite unit has a high/low setting on it and it seems to be optimized for MonoKote, so I use it for most of the work. The Coverite unit has a temp setting, so good for different film temps. I use it for doing trim schemes as can dial in the temperature needed to activate the adhesive, but not make the film bubble. Both have different “shoes” you can fit on, but again I prefer the TopFlite unit shoe and the feel of it over the Coverite so use it for all work other than layering trim over trim. Either will work just fine!
- Large sealing iron and sock. Coverite unit have a temp setting dial and maintains it accurately. There are others that are good too. A sock will prevent scatching the film surface.
- Heat gun
- Sharp single edge razor thin blades. Get a box of them at the Hobby Shop or hardware store
- Good set of scissors dedicated to only cutting covering film
- Straight edge (ruler or square) I still have all my old set squares from High School Architecture class and they work great for this stuff. That curvy one that I forget the name of works great for patterns and rounded cuts. French curve I think...too long ago. If you do any garage sales, keep an eye open for someone parting with these or a trip to the stationary store may be in order.
- Good surface to cut covering on. I use a desk or bench with a slab of drywall on top. Once it becomes hacked up, just replace it with a new piece. I have not had to for a few years so makes for an inexpensive cutting surface.
- Monokote Trim solvent. I use this to remove any “bleeding” of colours on the seams between colours at the seams. You can use it to activate the adhesive on Monokote over Monokote if doing trim schemes.
I could go into detail on basic covering, but you can search that out, or even read what is provided on the roll itself. MonoKote includes some instructions as well as working temperatures and assume the other manufacturers will as well. Some items to help you get a good finish:
- Leave liberal amount of excess material to work with when cutting out initial piece to use. 2-3 inches over what you actually need so that you can hold onto it well and be able to “snug it up” while laying it down. You will cut the excess off after edges are sealed. Better to have a little extra to hold onto as it will improve quality of cuts. I have large fingers, so need a little more to get them out of the way and properly hold when I am making the final cuts.
- Work from the corners to initially tack it down. I will typically do a half wing panel at a time with a seam in the centre section, starting with the bottom of the wing. Make sure the center cut is done using a straight edge ahead of placing it, then line the center up fist leaving a little for overlap. Try to get as much of the slack out as possible when you tack on the corners. The tighter you can get it without wrinkles, the easier it will be to shrink at the end. You do not need much to hold it on, and if you need to pull off, just add slight heat and pull off and re-tack. Once happy with the fit, begin slowly sealing up the edges all the way around, carefully avoiding wrinkles. Finish off with the heat gun working from outside in to get a tight finish. Use the larger sealing iron with sock to touch up areas needed.
- You will need to ensure you get an overlap between sections. As an example, I would cut the bottom panel off at the top of the TE of a wing and dead centre of the LE. The TE you wrap right around and seal it right to the top of the TE. Now run a “sharp” razor lightly over the top of the wing carefully not to cut the balsa while cutting the excess covering off in a straight line. This will take practice but the key is to get a nice, even, clean, straight cut. Now seal it off. The covering should basically come up the TE right to the top of the wing without overlapping the top of the wing. When you lay the top piece down, you can cut that piece halfway down the TE so the seam is hidden by the control surface that will later fit in, or you can bring it right down to the lower edge of the TE, and again use that edge to guide the blade for another smooth cut. Once sealed, you cannot see the covering seams...or makes for a nice transition between colours. On the LE for the lower panel, I would cut the bottom covering so it is centre of the LE or approximately thereabouts . The top panel of covering I would lap it over to somewhere on the lower curve of the LE for the cut/seam. Careful with the heat on the seams as you do not want to have it bubble, but you can work the very edge to the point where it almost melts into the lower layer. If the seam is straight and not jagged and positioned where the eye will not catch it, it can be almost invisible. This is one of the reasons why I like Monokote. But again this is a personal preference and what I am used to using! run your finger against the seam to feel if you can lift the covering...if you can feel it come away, then keep working it with the trim iron rounding out from the seam itself. Once you can go around the entire edge without feeling the seam or it lifting, you are good.
- Always work from the lowest point up. Bottom wing panels first then the top. Bottom of fuse, sides of fuse, then top of fuse. This will allow you to “hide” the seams. When looking down on the plane, the edge is not as visible as it would be looking from the bottom up. Since most people look down on the plane while it sits on the ground or a table, the seams are harder to see if done this way. Place them in the right spot and they will be almost invisible.
- On a squared off fuse as an example, when you cover the bottom, you can bring the edge up and around the curve, but not as far as to go onto the fuse side. As you lay the side panel down, you will overlap slightly to the under section. This will give you the overlap required plus tuck the seam under the plane. If you can cut the side panel to the lower part of the curve without overlapping too far onto the “flat” part underneath, the seam will almost be invisible. Again if you work the very edge with the trim iron, it will almost disappear.
- Try to position all seams where there is already a natural line. So sides and bottom are easy, but the final piece(s) on top are a little more challenging. Try to overlap right where the top curve ends and the side begins. Again, ensure the cut is straight and on that edge and it will not be as noticeable. Try to work with the biggest pieces of covering you can to avoid seams, but you cannot obviously cover a fuse in one large piece....well at least I cannot. Try to do the bottom in one, each side in one and the top you may need to do the back in one and front in another. Ultimately this will give you the least amount of noticeable seams.
- Tail Feathers. I usually cover with the stab and fin already glued onto the fuse. It is usually the first section to be covered. Where the fin or stab meet the fuse, I start with a thin long piece of covering that I crease and iron it in. Careful not to heat too much as you do not want to shrink the covering to where it pulls away in the crease. This is where a pointy trim iron tip helps to "seat" in the crease, then work out the 1/8 " on each side that will be overlapped. Do all creases then apply the flat sections staring with the bottom and cut the edge exactly to mate with the fuse crease. Seal that edge first, then proceed to seal the rest of the perimeter while avoiding wrinkles and ensuring it is all tight. Do the usual cutting, sealing and shrinking but be aware of the crease and avoid excessive heat or you will bubble or pull it away. Once done you will again have a seam that will go unseen.
- If doing patterns, cut out some templates out of light cardboard or something similar. I used some old photos for template material, then placed the template on the covering and cut out my piece. For the sunburst (red), I then placed them and marked off on the white finished wing where they will line up. Clean wing of any debris and then I remove the backing of the new covering piece and spray with Windex. Lay it down in place and start to work out the Windex and bubbles. Keep working it with your finger to get all the bubbles out. Eventually it will appear tacky and will no longer move around. Ensure you work all bubbles out!!!! Once happy with the result, let it sit for a few hours or even over night. Now, you can adjust the trim iron for a low temperature that will activate the adhesive, but not too hot that will make the covering “gas off” creating bubbles. Try a few test pieces on the bench to get the right temp for adhesion. Lightly work your way over the trim pieces. Flat sections are easier to do, like a stab, where wing ribs make it a little more challenging.
- Doing rounded wing tips is a little more challenging and requires patience. You basically need to stretch, heat and tack while holding everything. Slowly moving over the tip working it all around with the trim iron while pulling and stretching. This is where having five arms would help. Again try to tuck the top layer overlap seam under about 3/4 around the tip to the underside so it remains out of direct sight. This cut will take practice to get the covering to the right position and to the point where you will be able to make an even cut around. Once sealed, it is almost invisible. You will be surprised what you can get around without wrinkles if you take your time and work it slowly.
- Use the Trim Solvent to clean off any markings you may have added for lining up and bleeding of colour on seams.
- Finish off with either thin striping ironed on, or purchase pinstripe tape. I found the Great Planes pinstripe tape works well if you do not want to cut your own out of covering film.
- Keep the cuts straight
- Use sharp blades and dispose as required. I usually go through 6-10 on a plane while covering...they are cheap.
- Get covering as tight as possible and wrinkle free before you start heating to shrink.
- Use the appropriate heat for the film
- Try to strategically place the seams where the eye will not catch them.
- Take your time! It is important not to rush if you want a great finish. When I first got into building RC planes, I could cover a plane in a couple evenings with good results. It was more "assembly" line type of building. Now it seems to take much much longer, but I am REALLY happy with the results. Even though have more experience, and do some stuff faster, the planning and seam work is where I spend allot of time. I suspect you may be gathering this up by now.
Hopefully this will get you started as I have tried to highlight some key points. Check out the videos online as well. Good luck and don't be shy to ask any questions. Hope this was not too too long winded and makes some sense. I don't claim to be an expert, as have seen some amazing work from great modelers like at the Toledo Weak Signals Show, that are much better and more experienced, but hope this provides you some guidance that will get you going.
OK...the book is done!