bbells

I was bored the past couple of days during the snowstorm/icestorm/windstorm/rainstorm and started experimenting with my Minwax Polycrylic spray and my foam planes.
I sprayed 3 coats of polycrylic on 2 different planes. There was no fiberglass, silk, etc., added. Just the polycrylic.

I expected there to be no difference between coated and uncoated when I did the following test.

Weight:
My little Hobbyzone Champ increased in weight by 4% after spraying with 3 coats and drying overnight. That is significant, but probably won't affect flying.
The Hobbyzone Cub (the big one) increased in weight by .6%. A very insignificant amount.
The difference, of course, is most likely due to the weight/surface area relationship difference between the 2 planes. The champ only weighs 1.25 ounces before coating.

Strength:
Next, I sprayed 1/2 of an old Hobbyzone Cub wing with 3 coats of Polycrylic and let it dry for 24 hours.
I put a pad around the middle 6 inches of the wing, put a board on the top and bottom (measured to confirm middle), and securely clamped it to a table. I made sure I didn't over tighten.
Next I put a 1" wide strap 3 inches from the end of each wing. I hung a 5 gallon bucket from the strap.
I did the uncoated side first. It took 48 ounces to break the uncoated side of the wing.
The coated wing took 79 ounces before breaking. The first thing I noticed is that this side bent twice as far as the uncoated wing before breaking.

Both wings broke the same distance from the center. In this very unscientific test it took 64% more weight to break the coated side of the wing.

My summary: Ok, I think we all agree that the test surely had problems and is not entirely accurate. And, I am sure there are techies that will find fault with everything I did. And, the wing may have had some defects since it was older. But, lets say the test was 50% off - Which would be a lot. This still means the coated side was 32% stronger than the uncoated.

After considering the following, I figure I should use it on several planes:

1) The coated wing can take 30-64% more weight stress, and can bend twice as far before breaking.
2) The abrasion protection is significant. My planes will look better longer.
3) The weight difference on larger planes is negligible.

So, that was my test. Yes, cabin fever causes us to do strange things. But, this was better than eating or shoveling ice all day.

GallopingGhostler

The Ringmaster's Brotherhood CL forum users have positive comments using Polycrylic to coat porous covering materials and balsa. Seems to be nice stuff although a bit pricey. It is probably the stiffening of the surface that helps to add a certain amount of strength to the foam. The greater value I gather is use as an preparatory sanding sealer undercoating to accept a final painted finish. I have no experience with the stuff yet, but might get some down the road to try out.

pdansalvish

My Feedback: (23)

I use it on all of my fosm planes. But, I buy a can of flat and apply two coats with a cheap foam brush. I found it adds some protection to the plane and if it is a warbird it helps dulls the finish.

coupe1942

I absolutely love this MinWax Polycrylic satin clear product. I use a light 3/4 oz fiberglass cloth (feels like tissue paper, but very strong) on my SC. I have stripped off the decals on the floats and coated them with the MinWax Polycrylic. I use a china brush, but you don't want the stuff to pool, so a sponge brush is likely better. My local Lowe's is stopping selling their water-based coverings, so they had only one 1/2 pint can. The stuff is not overly cheap. I believe it was about $8-9 bucks for a 1/2 pint can, but that lasts a long, long time. I have also put on a Plasti-coat to the wing tips of my SC. The MinWax dries clear and does not show unless you streak it over decals and leave brush strokes. This stuff is soap and water clean up, so you can easily use the brush over and over once cleaned. Although I used reinforced packing tap on the leading edges of my SC, I also coated them with the MinWax by itself and not the fiberglass cloth. It probably does not make the plane indestructable, but it sure helps with the durability and does not add anything significant to the weight of the plane or the CoG. I have also done up a couple of cowls as spares by using this product and some fiberglass cloth or even some of the yellow tape used in plastering wallboard. I paint the finished cowl after the grille mods are completed. Here is a link to my flickr set. It shows some of the stuff I am doing, even some mistakes I may have made. Using the Minwax product is not a mistake though. It is one good mod for the SC or other rc planes in my opinion.

http://www.flickr.com/photos/a1930fo...7635439959912/

Although these flickr sets are more about diy camera mounts for my SC, they show the plane enough that you can see how it looks with the MinWax applied:

http://www.flickr.com/photos/a1930fo...7635701860576/

http://www.flickr.com/photos/a1930fo...7635023215356/

Last photos are on this link:

http://www.flickr.com/photos/a1930fo...7635240076898/

Glacier Girl

My Feedback: (4)

Another benefit is to seal down your decals and stickers after applied. No more peeling.

Minwax,and be careful to use the water based (WBP)and not the solvent based, as the solvent based can eat some foams. But it can be used straight, with fiberglass, and even paper to give you a glass like finish. Proper prep and sanding are paramount to getting there. If used straight, mix in some talcum/ baby powder to help fill rough spots. Makes it easier to sand and gives off a nice odor.
You can even mix in light weight Spackle for fill coats.

Here's my E-flite Super Airliner, done up with WBP/glass/paper. Check out the reflections in the paint, no bumpy surface there.

YAT-28E

GG

That's one nice Jet!! You mentioned paper, like newspaper?? Also what paint did you use??

Mike