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Consider using a Mylar film to improve the durability and appearance of your Dacron skin

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How to Cover with TOP FLITE- MonoKote 4/30/97

This material is an alternative to paint or varnish for sealing the Dacron. It provides a super smooth high gloss finish that is available in 46 colors plus clear. It adds strength to the fabric because it is PUNCTURE and SCRATCH RESISTANT with high tensile strength of 25,000 psi. Now don't get carried away by that figure, it is only 1 1/2 mils thick. They don't say what plastic it is but my guess it is probably MYLAR. It is a surfacing skin with its own adhesive that is activated with heat (an electric iron). It sticks to the Dacron surface but does not flow into the weave of the cloth and therefore lets the Dacron retain the bare fabric, individual fiber stretching, tear resistance. That high tensile strength is obviously a lot greater than any kind of painted surface.

WHEN TO USE MonoKote: while these boats are not designed for White Water they have successfully done it with minor damage. So for White Water or places with Dead Falls and snags are worth considering this technique. The great high gloss color selections of material lends to wet, wild look "paint", with no limit on graphics. The result looks like an expensive Imron paint job. It is a lightweight film that only adds one-fifth ounce per sq. ft. Because it is odorless and has no dangerous fumes it fits right in with the philosophy of building a boat in the apartment.

Now let's get down to business, it all may sound a bit fussy but it is quite forgiving. I don't claim to be an expert Monokote installer. I mumbled through the procedure, inventing some techniques and made some stupid mistakes. The bottom line was the completed boat; it really looks sharp. An expert model airplane builder would probably laugh at my so called "professional" instructions. Anyway I'll explain how I did the job.

While mucking around with test panels I made an interesting discovery. I was not overly pleased with the peel test quality of the Monokote to Dacron. It was stuck down and the overlaps were terrific; but if you got an edge up it was not too difficult to peel the stuff off. Now I've told you in the instructions, while building the boat, to varnish the woodwork prior to installing the Dacron. So now it should be no problem that I'm going to tell you to scrub the Dacron with clear water and a Scotch Bright pad and let it dry. This would be kind of sloppy in the living room so take it outdoors. This smooths down the texture of the weave and I guess provides more flat surface for the Dacron to stick to. How much to scrub? Do it thoroughly over every square inch pressing firmly with 5 or 6 back and forth strokes. If you make up a test frame, suggest 8'x8 with 3/4" sq. wood and cover with scrap Dacron. Scrub half, let it dry and study the surface, you will see a different texture and the weave seems to flatten.

The real secret to this material is its ability to seal to itself with an almost invisible seam. Because of the limited ability to heat shrink it must be applied in "plank" fashion. This is not a difficult problem but it does take more time than doing the Dacron. I would say that we have been spoiled, because the Dacron is so easy to do. Overlaps should be a min. of 1/4" and not much more than about 3/4". The only problem with excessive overlap is, it can cause you to trap air bubbles. On the overlaps work the iron progressively towards the open edge to expel any entrapped air. Of course, there is no problem with entrapping air on the Dacron itself because of its porous nature. And that is why the Dacron must be left un-sealed.

Monokote is supplied in two sizes: 6 ft. & 25 ft. rolls x 26" width. To "plank" a boat you have to first cut out a "plank". Before you are ready to purchase the material you should measure how much and what size to get. It will work out best to start at the keel and work up. This places the final overlap on the bottom edge where it shows the least. I suggest that you experiment with some stiff brown wrapping paper and make a template of the rough shape to see what you are dealing with. You need to determine how wide to make a "plank" so that it will completely cover the width of one bay between two stringers. You are going to discover that some of these "planks" have quite a curve to them. You can simplify the process and minimize waste quite a bit by not using full length "planks". An overlapping (1/4") butt joint will hardly show.

The hardware stores sell a small plastic gadget called "SNIPPY", it holds a double edge razor blade and it works very well to trim this stuff with a nice smooth edge. I set up a cutting table and clamped down a straight board as a guide. Now I'm treading on thin ice when I suggest using a panel door borrowed from my wife's sewing room as a smooth cutting table.

Now here this! Like a lot of plastic materials, MonoKote is notch sensitive. What I mean is that it is tough and hard to tear unless you create a cut; then it will rip like tissue paper. So the trick is to cut the stuff with nice smooth edges. Use a razor knife or at least make really clean scissor cuts . . . no jagged edges. Bear in mind that the MonoKote is a replacement for paint or varnish, which also tears easilly; so don’t be alarmed about this weakness. The Dacron has a rip stop quality.

I didn't make any attempt to fit the "planks" with the appropriate curvature, I simply used rectangular shaped pieces of the material. The uneven overlaps did not show that much. A nicer job with less waste material would be to trim each piece to match the curve of the stringer.

Running through the process in my head, I might suggest that with some extra helping hands to hold the ends while you worked (you need two helpers), you could partially stick the material in place and then trim it right to the curve. This will eliminate a lot of waste because the cut off curve from the last "plank" will just about fit the required shape of the next piece. That SNIPPY tool would be easy to use, following around the curve of the stringer.

THE LEARNING CURVE! On the next boat that I did (the Westport Dinghy) I got a little more optimistic about the shrinking ability of the stuff and tried spanning two "planks" with one width of the MonoKote. The trick seemed to be to stretch the material as tight as possible along the middle stringer before sticking it down. Lay it in place; then peel out the poly keeper from underneath. Pull like hell on the four corners and adjust it sideways to even up the wrinkles on the outside of both "planks". Heat shrink the sides of the "plank" so that it lays down flat but not really stuck to the Dacron along the stringers. You will want to get under this edge in the next step.

Here it gets a little fussy, I slipped a plastic guard (a piece of .005 mil Mylar, about a foot long x 1" wide) under the edge of the MonoKote so that I could not cut the Dacron . Now I carefully cut off the excess with a razor knife and a metal ruler straight edge... A series of short straight lines made a nice looking job. Now iron it down tight to the stringer area.

While experimenting with larger widths of MonoKote I got into heavy duty compound curvature in the bow area. I tried using a heat gun for the shrinking and had mixed results. It does work quite well but it is tricky because of the distinct possibility of burning a hole...I did burn two small holes while working on some really stubborn wrinkles. Not a total disaster, the patches hardly show. The trick is to watch with an Eagle eye and keep the gun moving!

MonoKote instructions tell you to set the iron at 275 deg. temp. It is not a bad idea to experiment with the iron on that sample test frame that I told you to make. My iron melted the Dacron on the wool/cotton setting so I went back to the the dot between rayon and silk. That measured between 320/340 deg. a little higher than the 275 deg. seemed to stick it tighter to the fabric. MonoKote sells sealing irons and they have neat little cotton booties to use as a softer surface to avoid marring the skin. I tried simply ironing on a cotton handkerchief and that worked fine. The worst mistake that I made was on the first piece that I ironed in place. It didn't seem to be stuck on all that well, it was then that I discovered that I had forgotten to remove the protective poly material that is used to cover the adhesive. I guess this only goes to show you how forgiving this stuff is, I peeled it off, removed the poly skin and ironed it on again for a successful job.

Along the edge of each piece that goes on requires a bit of fussing because it becomes a compound shape due to the angle going around a curve. The iron will shrink up that much so that it lays flat. The only problem is to work progressively towards the edge so that you don't trap air bubbles. If you do trap a bubble it is almost impossible to squash it flat, I had some success with a needle point carefully piercing the outer layer to let the air out while ironing down.

Pay carefull attention along the Gunwales to avoid re-heating and loosening the HeatnBond tape that holds the Dacron in place. Just run the iron along the Gunwale 1/2 width at a time.

The ends of the boat should have an overlap onto the front face of the stem. This may be a little bit too much compound curve and require some tabs to be cut. Stagger the tab cuts from one side to the other so that you maintain water tight integrity.

You can create all kinds of graphic designs by adhering different color MonoKote over the surface. Here is where you must be careful to not trap air bubbles if you use wide pieces. TOP FLITE also makes a special trim grade of the material that is adhesive backed, just peel and stick. This is supplied in 5" x 36" sheets (23 colors).

I can't say that this is the only material that will work for this purpose; however I did test a few competitive products with poor results. MonoKote is sold in most good model supplies stores. You can also mail order it from:

TOWER HOBBIES
P.O. Box 9078
Champaign, IL 61826-9078
800-637- 4989 for orders
800-637-6050 for assistance

TOP FLIGHT MonoKote is distributed by:
GREAT PLANES Model distributing co.
P.O. Box 9021
Champaign, IL 61826-9021

(Look for a color chart in RCM Radio Control Modeler Magazine)

MonoKote Update

I really hate it when this happens! July 23, 1997

The message here is to store your boat under cover when not in use.

The first boat that I applied MonoKote on was done in late 1994 and it still looks great. I did the suggested procedure of keeping the boat under cover to protect it against UV degradation when not in active use.

The can of worms was opened last December 7th when I made a test panel of black MonoKote on Dacron and placed it outdoors for an exposure test. Late June I discovered some lifted areas and ironed them back down. It was attributed to the very high heat that was building up due to the panel being laid on a flat surface and trapping the heat.

Two weeks later upon a more complete inspection it was discovered that the MonoKote had become brittle and will fracture when stretched. . . like pressing a finger onto the surface.

Go back to the first boat, the stuff is doing fine just give it a break and keep it under cover when not in use.

A friendly awning maker suggests applying a product called 303 PROTECTANT that contains UV screening and is available in marine supply stores.

I applied a very thin coat by spraying it on in patches and then rubbing it out with a rag to a uniform coat that dulls the high gloss a little and ends up kind of iridescent and streaky looking ... Especially bad on black—not too noticible on other colors.

I’ll say this for the 303, it is mighty hard to wipe off. Wipe and rub on the black MonoKote and the iridescent effect persists. This tells me that it will probably last quite well.

WARNING: Do NOT Cover a man-carrying aircraft with MonoKote!

It only sticks fairly well to the Dacron. This is no real problem on a boat, but can you imagine a bubble of this stuff lifting off the fabric from negative pressure, like on the aft surface of one wing panel! The situation would be worsened by the high tensile strength of the material. I call this problem the Steve Whitman effect...don’t get caught by it.

Very truly yours,
Platt Monfort

 
 
 
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