Well, they don't stretch like hoppy described the paper to do. I've been able to still get decent results though, like the nose of the jet. There may be a few wrinkles involved, but if you make sure and brush them down they can be sanded and minimized. I can take a picture later tonight or tomorrow to show a closer view but I thought it came out really well.

The photo below is a recent build I did of the "Porco Rosso" plane. It's totally covered with the filters (except the motor pod) and I think the curved areas come out ok.

I should point out it doesn't stretch a lot, but enough to take care of minimal curving. On large curvatures, I use a bunch of small pieces that almost lie flat. Like on the nose of this ME163.
Before and after sanding and painting.

Originally Posted by billwhit

If it helps at all, I just covered my Redi-Jet Sport with the Polycrylic and coffee filters. I know this isn't an extremely popular method, but it's what I do. Anyway, this 25" WS jet gained about 2 oz from the covering. Also, the Filters become transparent once applied. The photo attached is fully covered.

Thanks guys, this is some fantastic information! How do you guys use the coffee filters, without getting the round shapes of the filters in the final product? Cut them to shape? Some sanding? I'm new at this stuff, if you can't tell

Originally Posted by pdiddyg40

Thanks guys, this is some fantastic information! How do you guys use the coffee filters, without getting the round shapes of the filters in the final product? Cut them to shape? Some sanding? I'm new at this stuff, if you can't tell

I cut them into rectangles and overlap them just a bit when applying. Then once it's all dry I sand it really good and give it another coat of Polycrylic. The first time I did it I left them round, but you get a lot more unwanted overlap that way. Working around the edges and joints takes a little practice.

Recently I stopped by a restaurant supply shop and they had boxes of filters that are much larger than your normal ones, but I had to buy a huge box of them. So I haven't made that purchase yet and still use the standard ones you can get at the grocery store.

Thanks for the information. We'll see how quickly I can get this job done

Originally Posted by larryross

... If done sparingly it might add 1.5oz per square foot or less. This isn't for a plane where weight is a major factor...My Chubby Cubby build almost doubled in weight

Aha!
That is the answer I was looking for since post #1: what kind of plane are these guys talking about?
I am a noob, I build with depapered elmer's board (only option within 2,000 km), but I want to stick to a cap of 3 foot wingspan and 17-20 ounces to my e-rc's "with the tanks full".

My 38" span ME163 with a full solid foam body and symmetrical (2 pieces of foam) wing weighs 19oz without a battery. All surfaces covered with newspaper (Post #32).

Brilliant MOVE !!!!

Coffee filters are produced with 100% softwood, Pine, and also treated with a wet strength agent, Kymene, to re-inforce the strength when wet. They are very stable when wet and generally do not experience any cross sectional instability when subjected to moisture.

Originally Posted by billwhit

I use Polycrylic and coffee filters to cover my planes. The filters don't shrink when it dries so I haven't experienced warping of parts and I've covered at least 8 planes this way. It makes me wonder if the unprinted newspaper would be the same using polycrylic? I guess it depends on if it's the nature of the paper or if it's the water causing the shrinking...

The water causes the paper to relax so when you squeegee out the bubbles it stretches the paper, when it dries the paper tries to find it's original size this shrinkage which isn't all bad as it draws tight much like heating monocoat, but if too much shrinkage then warping and bending will happen.
I haven't tried coffee filters yet, but it is on my list of to dos.

Originally Posted by onio condor

Brilliant MOVE !!!!

Coffee filters are produced with 100% softwood, Pine, and also treated with a wet strength agent, Kymene, to re-inforce the strength when wet. They are very stable when wet and generally do not experience any cross sectional instability when subjected to moisture.

Okay, so nobody has so far done a before and after test on the mass of the reinforcing materials? hoppy, do you still have the piece you used in the first post? Can you weigh a piece of naked foam the same size and compare that to the piece you treated? I'd still like to get some sort of delta per area so that we can all project what planes will weigh based on their surface area. You can do that now with naked foam or FFF with the skin on it, but you can't do that if you don't know what the paper covering weighs.

I have used the mini wax Polycrylic and Silkspan (tissue) on most of my
foam models, with very good results, the tissue conforms to curves
and like the other methods mentioned it add's stiffness.

short video on how I do it.

ployglass.wmv (3 min 2 sec)

on my last model an EPO foam model, I did have a problem
with the tissue lifting from the foam , while I was able to repair
the damage , I'm now working on a new way of securing
the tissue to the foam

Here is what appears to be rolls of filter material. Can't find a price but would be easier than cutting up coffee filters. http://www.ecplaza.net/trade-leads-s...--5553549.html

coffie filter paper and heavy sillkspan are about the same ,
silkspan comes in diffrent weights..


http://www3.towerhobbies.com/cgi-bin...?&I=LXR757&P=7

http://www3.towerhobbies.com/cgi-bin...?&I=LXKRU2&P=7

http://www3.towerhobbies.com/cgi-bin...?&I=LXR759&P=7

there are other sites that sell smaller amounts tower also
didn't show the heavy silkspan in stock

http://www.sigmfg.com/cgi-bin/dpsmar...FV5.html?E+Sig
look at covering /tissue

Originally Posted by A Useless Geek

Okay, so nobody has so far done a before and after test on the mass of the reinforcing materials? hoppy, do you still have the piece you used in the first post? Can you weigh a piece of naked foam the same size and compare that to the piece you treated? I'd still like to get some sort of delta per area so that we can all project what planes will weigh based on their surface area. You can do that now with naked foam or FFF with the skin on it, but you can't do that if you don't know what the paper covering weighs.

You'll have the info tomorrow.

I used the (1) Wet the foam with 50/50, (2) Apply paper dry, (3) mist paper till damp, and (4) Squeegee with credit card to remove excess glue on a piece of $Tree foam and got the following weights.
Wt of $Tree foam - 18g/sqft
Wt of foam with one side covered - 25g/sqfy
Wt of foam with both sides covered - 34g/sqft.