Polyspan or polyt

[donald raab]

Is there a grain in the product like silkspan or silk.  How many coats of clear befor filler or paint?  Not looking for a front row finish.  Just sport.

[keith varley]

You mention  silk  polyspan and silkspan.They are each vastly different. Silk is cloth.The fibres are made by moths. IF you unravel a cuccoon , you get a strand of silk , and by weaving it into cloth , you get silk. Real grain , just like your handkerchief. Comes in many grades and types and can be expensive. Light weight.It takes some skill to apply silk , and you really need to carefully get all the fibres lined up in straight line for cosmetic reasons.
   Silkspan is a paper product. Exactly the same material that tea bags are made  from..Available in usually three weights.It tears easier in one direction than the other , so in a sense it has grain.It shrinks when whetted or when doped. Must be sealed with dope , or it has little strength , and is not air tight.Silkspan is the cheapest of the three and the easiest to use.
Polyspan is almost the same as silkspan in a way except it is polyester fibres.Much stronger than silkspan and must be shrunk to be taught , and sealed with dope to make it airtight.Can be torn easier in one direction than the other , just like silkspan.It shrinks with the application of heat , as from a heat gun.
Also a plane can be covered with iron-on plastic material like mono-coat, or numerous other brand names.Iron it on, shrink it tight with a heat gun.Comes already coloured and is fuel proof. Requires no doping .
Silkspan, polyspan or silk all need at least four coats of clear before applying coloured dope or spray paint.
   There is a learning curve to the use of any of these products.Considerable skill even.

[Paul Smith]

Polyspan is like a plank of AD wood.  It has both a grain and a top & bottom.

You need to make the grain spanwise and the shiney side up.

I've had some on racers for five years.  It's a heat shrink material.  Like you said, it may not be stable enough for a first rate finish. 

[Randy Powell]

>>It shrinks when whetted or when doped.<<

It actually expands when wet. It's shrinks as it dries. Which is why you wet it, attach it, then watch it pull taunt as it dries.

Just sayin'

[Larry Renger]

Some silk does shrink when wetted, and can be applied dry.  Other silk only expands then returns as mentioned above.  Wet application will always give the best result with either one.

Just a hint, I lay the silk dry on the surface, spray it with a mister, and then pull it in place.  Much easier than trying to handle a wad of wet silk. 

[Paul Smith]

My process for Poly-spanning to the dope and sand the frame very well.

Then place tbe Poly on dry usin g plastic clamps around the perimeter as weights.  This gets all the wrinkles out.  Then I go around the edges with a brush & thinner.  Thje thinner liberates jsut enough dope to stick it on.  If all goes well, I follow up with a good