Working with Light Polyspan

LIGHT POLYSPAN

6’ x 39” $13.00

THERE IS A GLOSSY AND LESS GLOSSY SIDE. THE SMOOTH GLOSSY SIDE IS THE OUTSIDE (UP). Run grain spanwise!

APPLY AS YOU WOULD FOR SILKSPAN BY PREDOPING THE PERIMETER WITH TWO COATS OF DOPE AND MORE COATS ON THE BOTTOM OF THE RIBS IF THE WING IS UNDERCAMBERED. LIGHTLY SAND THE DOPED AREAS.

CUT THE MATERIAL OVERSIZE, PARTICULARLY AT AN ELLIPTICAL SHAPED TIP, ETC.

APPLY BY DOPING THRU THE MATERIAL. I NORMALLY USE THE MAIN SPARS FOR FIRST ATTACHING IT, THEN DOPE THE LEADING OR TRAILING EDGE. NEXT, PULL ANY EXCESS MATERIAL OUT. IT DOESN’T HAVE TO BE TIGHT AT THIS TIME. DOPE EACH UNDERCAMBERED BOTTOM RIB AND RUB DOPE THRU THE POLYSPAN, ADHERING IT TO THE RIBS .

CUT THE EXCESS AROUND THE PERIMETER SO YOU WILL HAVE AN OVERLAP OF ABOUT 1/8”.

USING A MONOKOTE TYPE IRON, ROLL THE EDGES TO HELP THE MATERIAL FOLLOW THE CONTOUR. THEN DOPE IT DOWN AND RUB THE DOPE IN.

DO THE SAME FOR THE TOP ON THE WING. WHEN DOING AN ELLIPTICAL TIP, TACK DOPE SEVERAL SPOTS ALONG THE TOP AS YOU WOULD FOR MONOKOTE. ADD WEIGHT OR HAVE SOMEONE ELSE HOLD THE WING. THEN WHILE PULLING ON THE EXCESS WRINKLE AND HOLDING IT OFF THE SURFACE OF THE WING, HEAT IT WITH THE IRON AND IT WILL STRETCH--AND THEN PUSHING IT DOWN WITH THE IRON, IT WILL CONFORM TO THE CONTOUR.

THEN DOPE AND TRIM THE EXCESS.

THE DOPE WILL SHRINK THE MATERIAL BUT I USE THE IRON TO TAKE OUT ALL THE WRINKLES BEFORE DOPING IT.

PUT TWO TO FOUR COATS OF DOPE, PREFERABLY BRUSHED ON With A Foam Brush!, Thinned about 50%. (DON’T THIN TOO MUCH FOR THE FIRST TWO COATS) THEN IF YOU WANT COLOR, USE THE POLYSPAN DYE, MIXED 1 PART DYE, 1 PART CLEAR BUTYRATE DOPE AND TEN PARTS BUTYRATE THINNER AND SPRAY THIS ON.

(NITRATE DOPE AND THINNER DOES NOT MIX WELL WITH THE POLYSPAN DYE) USE PARKS OR SUNNYSIDE EPOXY & LACQUER THINNER FOR NITRATE DOPE, AVAILABLE AT HOME DEPOT AND TRU-VALUE

SPRAY ON A SEALING COAT OF DOPE. JAPANESE TISSUE OR COLORED DOPE CAN NOW BE APPLIED FOR TRIM IF DESIRED. THEN I BRUSH ON AS MANY COATS OF DOPE TO GET THE GLOSS I WANT (USUALLY 6-7 COATS) TOTAL.

APPLY FUEL PROOFER IF NITRO FUELS ARE GOING TO BE USED.

I SELL THE DYE. SEE MY LIST, SASE OR EMAIL ME FOR IT: samchamp@jetbroadband.com

Larry Davidson

More Polyspan covering techniques are taught by Dave Platt in his B2B (Back to Basics video)www.daveplattmodels.com/Video/index.htm