andrew66

hey, im wanting to try covering a plane with WBPU (water based polyurethane). ive heard that u can do it the same way as using dope. the reason i want to do this, is the lack of fumes. im only in a 1 bdrm apt, so i dont want to gas myself out. if anyone can give me a few tips, that would be great. maybe i could "wing it" and post a step by step here.

dhal22

use fiberglass and wbpu for covered areas and use koverall over open areas. u can shrink it like monocote with an iron. if you are using koverall be sure and apply stixit 1st as instructed. apply and shrink the koverall then begin the wbpu process. i have seen where some are using a hot blade to cut the edges to 'cut' down on the koverall fraying. open bays a very hard to sand so i recommend long smooth strokes to smooth the poly. for faster weave fill in i pour some poly into a different container and mix heavily with talc. good luck.

david

andrew66

i was hoping to not use stix it at all. it has nasty fumes as well.

TexasAirBoss

My Feedback: (22)

They all have fumes, don't they ? The dope will certainly poison you half to death in an apartment. But it dries so fast, about 30 minutes, you could run outside, apply the dope, let it dry before you bring it back in. The beauty of dope is that it dries so fast.

andrew66

only problem with doing that, is its getting pretty cold here in canada. soon it will be consistently about -10, which is way to cold to paint. i was hoping to use the WBPU and paint with latex. the fumes off this stuff is hardly noticeable, and i would only have to crack a window for fresh air. i only have limited access to a shop. but i was thinking about using the monokote clear spray for a top coat to protect the paint from fuel. i will be using a gas glow mix, so i might even get away with WBPU as a clear coat, cause i will be using little to no nitro in the mix. i think that tonight, i might try covering a scrap piece to see how it turns out. its an aileron from a scratch build that i have put on hold, so if i mess up, im not out very much.

andrew66

i figured i would just go ahead and try it. i took some pics of the process. a video would have been better, but i dont have a video camera. anyways, i started by brushing a coat of wbpu on the outside frame work of the aileron, then laid the koverall over and rubbed the koverall with my finger, so it would stick down. then i brushed a coat of wbpu on top of the koverall to ensure enough coverage. now i will let it dry (they recommend 2 hours) then i will do the same on the otherside. im just going to trim the ends, and just flip the piece over so that its done in one piece. not as many seams to worry about. after that dries, im going to do final trimming of the end so that i can attach them and seal them down. once that is dry, i will use my iron to shrink the fabric. hopefully this turns out, and we can all learn a new method for applying fabric.

andrew66

well, the wbpu is dry, so i tried shinking the koverall, and it worked beautifully! the aileron probably needed to be sanded a little better, but this was just for testing. i was afraid that the wbpu wouldnt hold when the covering was heated, but it worked. another plus is if there are any bits of overlap or a part that didnt stay stuck down, just iron it like u would with sitx it. now i just have to do the ends. i think if i were to do it again, i would have covered them first, then trimed and just had a wee bit of overhang on the top piece. oh well, i thought it turned out alright for a first try. im sure after doing this a few times, i could do a way better job, and it would go quicker. like they say "practice makes perfect"..... or close to it.

bps

My Feedback: (3)

Here is how I covered my Sig 1/4 scale Clip Wing Cub using Koverall and a latex glue/sealer named Mod Podge available from Michaels Crafts and other stores. I used this product thinned with tap water to seal the airframe with. This sealing process started with a sanded airframe and then the first coat applied with a foam brush. After drying a light sanding using about 400 grit paper. Tac cloth this clean and apply a second coat. Let dry and my plane did not require another sanding. Next step use a tac cloth again to remove any dust, then cut fabric oversize for the area your covering. Apply thinned Podge to framework around perimeter of area to be covered and lay fabric on plane while still damp. Apply more Podge as required to hold fabric in place and smooth out any wrinkles before fabric dries to airframe. After this dries trim Koverall with a sharp X-acto or some say a single edge razor blade works better. Make sure that the edge of the Koverall has been coated with the Podge and dried. This prevents most of the fabric fraying that is a real problem. Use a Monocoat iron to iron down the edges of the fabric. Apply more glue if needed under the covering to secure it. I now use the heating iron during fabric application when gluing it down to set the adhesive. This works well but you must clean the iron often and not use to much heat or you will make a real mess! After all fabric is applied I shrink the fabric per instructions included with the fabric. The fabric can be sealed with the thinned solution of Podge, just make sure you use a very light coat or it will form puddles on the back side of the fabric. Takes about 3 light coats to fill the weave. A very light sanding may be required after the last coat and then a final thinned coat. Remember to always use a tac cloth to remove any dust before each proceedure. Your now ready for the latex paint. With no SMELL!!!! I did mine inside in the winter. Words of caution. When sealing the framework your using a water based sealer (Podge) so it will be very easy to introduce warps. You have to plan for this on the light structures such as tail feathers. Also the shrinking process of the Koverall can crush or warp structures as the shrink factor is much greater than the plastic films and even the other fabrics we have used in the past. It does take time to do this, no instant gratification like cover with film and fly covering. Fell free to ask any questions if you would like. Hope this helps.

andrew66

that seems like a good method as well. it kinda funny how us modelers can find everyday products that are suitable to use. i really like the low odor, and easy cleanup of waterbased materials. do u run gas? or what type of clear coat do u use to make it fuelproof. i would hate to have a nice paint job ruined cause of fuel residue.

dhal22

nelsons clear is generally accepted as the best clear coat out there.

david

bps

My Feedback: (3)

Gas could topcoat with water based poly. Nitro will need either oil based poly (this will yellow) or Nelson's which seems to be the best choice.

smkrcflyer

Looks like I'm going to try koverall on my cub. Andrew66 hows the wbpu working?

andrew66

i havent covered an entire plane with it, but the test i did worked out well. its fairly straight forward, and no odors. give it a shot on a test piece and u will see what i mean. good luck

somegeek

My Feedback: (2)

Nice thread!

I'm currently trying a similar covering method for the first time with sanding sealer, WBP and 5mm Habotai silk. I have a guinea pig piece of silk on a three bay test frame made from scrap. Just got through tacking on the silk to the frame with WBP. Waiting for this to dry and will then hit the open areas with WBP and an airbrush. From what I've read, this should make things taught. Looking forward to putting this covering on my 1/2 Sure Shark. Covered a few planes with Ultracote. Time to try something different... that and silk/Koverall/etc covered planes look damn nice!

andrew66

feel free to post your results. i noticed that the wbpu usually is dry enough after an hour. i wonder how well this stuff holds up to 5% nitro? ive read 100s of post about it, and get mixed results. i guess another experiment is in order

somegeek

My Feedback: (2)

My results sucked.

That saves me some typing.

Adhering wet silk to my open bay test frame worked well. The silk drew taught when dry. I then applied some WBPU to the open bay silk and it sagged even though I drew it tight initially. It appeared to dry before the shrinking occurred. Not sure if I shoulda done something different?

Sounds like WPBUs friend is Koverall or any other cloth like covering which has heat shrinking abilities.

At any rate, I'm done fooling around so I put in an order to VHS for butyrate dope, white butyrate primer, dope retarder, maroon and cream butyrate dopes. Picked up a quart of quality lacquer thinner at Miller paint.

somegeek

bgfireman

My Feedback: (13)

andrew66,
AI was just wondering if you have covered your plane yet with the wbpu yet. If so how did it turn out? When you mix it with the water approx. how much water to wbpu do you mix.
Thanks
Alan

Broken Wings

My Feedback: (20)

I use regular SilkSpan in various weights and Polycrylic. It works Great. I may never go back to iron on covering.

dhal22

i keep monocote and other plastic coverings that i acquire in trades and such for the clear backing. it's good for layups and other epoxy work. other than that it's useless to me.

RCdude13

My Feedback: (6)

I'm doing my third warbird with WBPU. Make sure to seal the balsa sheeted areas so that the WBPU does not warp the balsa. I use minwax sanding sealer. On the first two planes I used fiberglass, but this one I am trying polyester dress lining. For $12 I got 3 yards of it at Walmart. A couple of coats of WBPU, talc and water filled in the weave. Sand it down with 320 grit for a smooooth finish. I then spray it with a light coat of high build auto primer. I'm going to try latex paint this time also.

andrew66

Im in the final stages of my build (kadet seniorita build) so i will be covering soon. I dont mix any water. just apply it full strength.
Rcdude: If you are using latex, i dont think that you will need primer. just make sure the surface will allow the paint to adhere. From what ive read, only 2 coats will fill the weave on fabric.

RCdude13

My Feedback: (6)

Andrew66,
The reason I use primer is for the panel lines and rivets. Once I have the WBPU and talc sanded down, I draw all the panel lines with pencil. Then I put chartpak tape over these lines. I spray 3 coats of primer over this tape and when you remove the tape you have panel lines. The primer is also good for showing any imperfections in the WBPU/talc coat, and it is the layer which I burn all my rivets into. I think you are right though Andrew...you could just as well paint right on to the WBPU/talc layer.

andrew66

i have never done a scale plane, so i didnt know what was involved with making panel lines. And if it shows imperfections, i guess it will make u do a better job. I learn something new every day

RCdude13

My Feedback: (6)

Andrew,
It really is surprising how many defects show up when you put a light coat of primer over the WBPU. Unfortuneately, it stinks pretty bad. The dress lining worked very well. Now I just have to figure out which latex paint is gas proof. I know that Behr from Home Depot is, however, H.D. is a 2 hour drive for me.

OldScaleGuy

My Feedback: (2)

I agree (for whatever that might be worth) that primer is needed on solid surfaces, i.e. sheeted wings, plank fuses, cowls, etc. Lately i have been using rattle can grey Krylon. It dries fast and sands great. Then on to the HD exterior latex. I am in the finishing process now on the first plane i have used latex and so far so good.