Oil Poly. vs Water Poly. vs Finishing Resin
 

Hello Everyone,

I have a dilemma. My dilemma, is that I have decided to devote quite a bit of time and energy in to researching, and building a very scale P-40E. (Wow...no one has ever done that before right?) :eek: In the course of this poject, I have opted to re-inforce/replace many of the kit's (Yellow Aircraft.) existing structures with carbon fiber or other composite material. This has hopefully resulted in a stronger internal wing structure. (Eg. laminated uni-directional carbon fiber spars, carbon fiber plate, aluminum scale hinging, and lightened g-10 composite ribs......etc....instead of balsa, ply, and robart hinges.).
That being said, I have been reading a lot about glassing with Polyurethane, rather than epoxy. To be honest, I love the strenth and rigidity epoxy provides. However, I hate the idea of how heavy epoxy will make my already overloaded plane end up. (So much detailing will enevetably hit me hard, resulting in a lot of added weight.)
In an attempt to find the best alternative, I have already done some tests. I have taken 1/10th gram, equal sized squares of balsa (from the same stock), and laminated them with several types of poly. I have also laminated a control with Zpoxy finishing resin. Each test sample was re-weighed after subsequent coats.

Z-Poxy: (.1 gram to start/no resin)
1st coat: .3 grams
2nd coat: .5grams
3rd coat: .7 grams
Result: Nice Dent Resistance/High Sheer Strength/Heavy Weight

AquaZar-Water Based Poly (Gloss): (.1 gram to start/no resin)
1st coat: .15 grams
2nd coat: .2 grams
3rd coat: .25 grams
Result: Little to No Dent Resistance/Low Sheer Strength/Light Weight

MinWax Oil Poly (Gloss): (.1 gram to start/no resin)
1st coat: .2 grams
2nd coat: .3 grams
3rd coat: .4 grams
Result: Little Dent Resistance/Moderate to Low Sheer Strength/Light Weight

Defthane Oil Poly (Gloss): (.1 gram to start/no resin)
1st coat: .185 grams
2nd coat: .275 grams
3rd coat: .385 grams
Result: Moderate-Little Dent Resistance/Moderate to Low Sheer Strength/Light Weight

ZarUltra Oil Poly (Gloss): (.1 gram to start/no resin)
1st coat: .185 grams
2nd coat: .285 grams
3rd coat: .385 grams
Result: Moderate Dent Resistance/Moderate Sheer Strength/Light Weight

In the end, my findings were rather disappointing. ( I do understand that I have yet to add the carbon fiber tissue and 3/4 ounce cloth, which provide the greatest structural strength in the process.) The only Polyurethane resin with any resistance to sheer forces or dents and dings, seemed to be the Zar Ultra. (Nothing to jump up and down about.) Admittedly, I have yet to try Zar's UltraMax poly, which apparently has the ability to cross-link with oxygen to create a harder and more thorough cure. (I will try this I am sure.) But what I am looking for, is a light weight, VERY hard and sheer resistant compound. Dropping a few hundred extra dollars on a 10k plane doesn't really bother me. Does ANYONE have ANY better information? It is my hope, that someone has experemented with some industrial or other professional form of high-tech compound (Poly or not.) that (aside from the price tag) will make me sigh with relief. [8D]

P.S. I haven't seen very many folks using oil based poly for glassing. Is there a sound reason for this?


Hopefully.....

Chris

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

I have used waterbase poly for glassing (MinWax Polycrylic). My experience with it has been as follows (using .5oz fiberglass cloth): The WB poly has about 60% of the strength of a resin job, about 35% of the dent resistance of a resin job, but only 1/2 of the weight of a resin job.

I feel that the glassing of a plane is to provide a stable, smooth surface for detailing/painting.

I feel that if you need the resin for strength, you need to go back and look at the airframe and re-enforce as needed.

As for dent resistance, you are not supposed to bang the plane against things :D :D , and if you "dumb thumb" it [&:] , I doubt even a resin job is going to be of much help.

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

Campy,

I can't really argue with that logic. :D You mentioned water base poly. Do folks use this strictly for the ease of clean-up, and lack of noxious fumes? Or do they use it because oil based poly doesn't "play" nicely with foam and primer/paint? I am tempted to use an expensive cross-linking, oil based poly, due to the fact that it seems to warp the wood less. It is also reputed to be "significantly harder, and more durable". However, if there are additional issues with this, I will likely resort to another even MORE expensive yet slightly less durable cross-linking water based poly. (My wife is going to kill me.)

Chris

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

Chris,
I have had success using the following combination without major weight gain, but yeilding a durable shell for painting.

1. Final sand with 320 (just trying to get it as smooth as possible),

2. Put on ONE coat of wood sanding sealer (specifically for use with poly to seal pores and reduces amount of
poly thats absorded), lightly sand when dry.

3. Apply your glass cloth with poly, same as you would if using epoxy, dab off excess poly with tissue or soft
paper towel, sand when dry. You will notice very little weight gain

4. Apply a thin surface layer of finishing or thinned laminatiing resin, scrape off excess. This just to help fill the
weave and provide that hard shell your looking for. You could add a little micro balloons to help lighten the epoxy
and make it even easier to sand, but not necessary.

5. SAND, FILL, PRIME and PAINT to your liking.

Try on a test piece of balsa I think you will be pleasently surprised.

Hope This Helps,
Keith

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

I used Campy's method of glassing my TF 182, but I used 3/4 oz cloth. From bare wood to glassed, primed, painted, and cleared only added 11 oz to this fairly large airframe. I've got a Piper Arrow II on the building board that is going to get the same treatment. It's soooo easy to use, is consistant, and easy to clean up. No sticky fingers, pants, and everything else you touch. I imagine it is also a bit cheaper.

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

Campy,

I can't really argue with that logic. You mentioned water base poly. Do folks use this strictly for the ease of clean-up, and lack of noxious fumes? Or do they use it because oil based poly doesn't "play" nicely with foam and primer/paint? I am tempted to use an expensive cross-linking, oil based poly, due to the fact that it seems to warp the wood less. It is also reputed to be "significantly harder, and more durable". However, if there are additional issues with this, I will likely resort to another even MORE expensive yet slightly less durable cross-linking water based poly. (My wife is going to kill me.)

Chris

< Message edited by ardrhi 4/25/2008 5:56:53 PM >

As meyersflyers said, the key is to use a sealer on the wood 1st. Here is a basic "How To" for glassing and painting with latex.

Hope this is of some help.



Glassing with Water Base Polyurethane


1. Sand the model with 220 grit and remove any highs/lows you may find.
Fill as needed with lightweight filler and sand.

2. Give the wood 1 thin - medium coat of wood sealer. I use the
commercial stuff. What this does is twofold - it stops the balsa
from soaking up too much of the poly and at the same time protects
the balsa from the water in the polyurethane.

3. When dry, sand lightly with 220 to remove the "fuzzies".

4. Some people say to apply a light coat of 3M #77 adhesive to the
wood at this point. I have found that this is more trouble than it
is worth since if you have a wrinkle, the complete piece of fiberglass
has to be removed to straighten it out.

I prefer to lay the fiberglass cloth on the part/area to be covered and
smooth it out using a SOFT brush. Brush FROM THE CENTER TOWARDS THE
EDGES. The static electricity usually holds it in place. I normally
use 1/2 oz (.5 oz) or 3/4 oz (.75 oz) fiberglass cloth.

5. Using WATER BASE polyurethane and a FOAM brush, start at the center
and brush towards the edges of the fiberglass. All you want to do is
stick the fiberglass to the balsa, so excessive amounts are not needed.
Any additional pieces of fiberglass should overlap each other about
1/2 - 3/4 inches.

Let this dry. DO NOT SAND !!

Brush on another coat of polyurethane. This coat can be a little heavier.

Let this coat dry. DO NOT SAND !!


6. Mix up some polyurethane and microballoons. I use 1 part
microballoons to about 5 parts polyurethane. This will be on the thick
side.

Brush on a medium coat of this mixture and let dry.

7. Wet sand this with 220 or 320 grit paper. BE CAREFUL, AS YOU CAN
VERY EASILY SAND RIGHT THROUGH THE FIBERGLASS.

8. Check the fiberglass carefully to insure the weave is filled. If
the weave is not completely filled, repeat step 6 and 7.

9. SPRAY a coat of water base polyurethane on the plane and let dry.
DO NOT SAND !!

10. Spray a THIN coat of primer on the plane. When this is COMPLETELY
dry, block wet sand with 220 or 320 grit as much of the plane as
possible to highlight any highs/lows you may have missed during your
sanding/prep. The areas that can not be block sanded, CAREFULLY sand
by hand. (TIP: CA some of the wife's/girlfriends fingernail file boards
together. Wrap the sandpaper around them so you can block sand in tight
areas. The CA helps prevent the boards from disintergrating in the water)
Fill any low areas with a lightweight filler and sand when dry.

Apply a THIN coat of polyurethane to these areas.

When the poly is dry, repeat this step until you are satisfied that all
the highs/lows are removed.

11. SPRAY a thin coat of polyurethane on the plane. When dry, spray
the primer.

12. When the primer is dry, you can apply your rivets, panel lines and
other detailing desired.

13. Now you can spray your paint.



Painting with Latex


First, if you have not done so, I strongly recommend you read the article
by Roy Vallencourt on using latex paint.
http://www.modelairplanenews.com/how_to/latex1.asp

I do disagree with Mr. Vallencourt in a couple of areas. These areas
of disagreement are based on my personal experience using latex.

1. I add 1 1/2 caps of FloTrol per quart of latex paint PRIOR to any
diluting. The Flotrol retards the drying slightly and allows the paint
to level itself.

2. Use ONLY water for thinning the paint. My experience has shown
that using windshield washer fluid gives a slight tint to light colors.

3. My best results with latex have been between 25 psi and 30 psi.
Under 25 psi I don't get the coverage I would like and over 30 psi the
paint starts to have a "dimpled" appearance.

4. I have not had good luck using a heat gun to promote quicker drying.
I know of several people who have had good luck using this technique
though. You can try it and see if it works for you or not.

5. I strongly suggest and highly recommend the blue 3M brand of masking
tape. What you want is the "60 Day Safe Release". This can be
identified by a paper appearance to the tape and on the side of the
wrapping is an adhesive index. You want a 2 dot adhesive rating. The
2 dot adheres reasonably well, yet will not pull up even fresh underlying
paint.

6. Flat latex will take an average of 7 - 10 days to "cure". Semi gloss
and gloss latex take 14 - 21 days to cure. To see if the paint is cured,
press your finger firmly on a hard area of the plane (I use the cowl
area). If a fingerprint remains, the paint is not cured. The
fingerprint will disappear in a day or two.

7. Gasoline powered planes will be fine with the paint as is. Glow
engine powered planes need to be clear coated. I suggest waiting until
the latex is cured before clear coating.

For clear coating I suggest one or 2 sprayed coats of a water base
polyurethane. My personal experience has shown that it is fuel RESISTANT
to 10% nitro and various reports indicate no problems with 15% nitro.
By fuel resistant, I mean if you let the clear coat dry for a minimum
of a week before exposing it to fuel AND you clean your planes at the end
of the day, you should have no problems. If you let the residue sit
overnight on the plane (or more than 4 hours), it will become sticky. If
you want fuel proof, use Ultracote or Lusterkote clear. Oil Base
polyurethane is also fuel proof, but it will start yellowing in about
6 - 8 months. The yellowing is not that noticeable on dark colors, but
very noticeable on light colors.

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

I follow the general instructions Campy layed out there,other than I have found that adding micro baloons wasn't necessary if after the 4th coat you give the surface a light sanding and do a couple more coats, the surface is very smooth.
as for personal product preference mine is satin sheen Varathane Diamond water based poly,its the hardest one I could find,generally used for floor and furnature finishing it can be recoated in a 1hr span,which allows the glassing job to be done rather quickly,and allows the product to have a chemical bond rather than a mechanical one.
I like the satin because I dont have to sand as much to dull the surface for recoating, slick surface means coats dont stick as well.
if left to dry more than a couple of hours then wait over night and lightly sand it before recoating its all detailed in the instructions.
I also use a decent 2" brush for application the job goes pretty quickly.
for sealing the bare wood I use Deft brushing laquer,incredably smelly stuff, but it does the job of sealing the wood,and sands to a smooth surface for the glassing.

after glassing I have been using www.warbirdcolors.com paints,and clear coats, with good results,fuel proof to 15% and water clean up.

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

I'll tell you what, I'm impressed with the ease and lack of fumes of the Minwax water based Poly method and I would have no doubts about using it on anything from about a .90 size down in order to save a bit of weight because it is more important as the size goes down. However, that being said, if I were building a larger plane, I think I'm going to want to use something a bit harder, not just to stabilize the balsa surface, but to also reduce the inadvertant "prang" that happens more frequently as models increase in size. I would probably choose to use polyester resin over epoxy too since I feel the polyester resin is harder when it cures than the epoxy and it sands a heck of a lot better than epoxy. But that's just my personal choice and everyone has their own favorite methods.

Now here is one thing most people don't mention when they talk about fiberglassing... the fiberglass cloths are treated with a sizing chemical, usually volan or silane, which is applied to the glass fibers to aid in the bonding of the resin to the glass cloth. These are formulated to work with polyesters or epoxies or both. These resins chemically link to the sizing increasing the bond strength. Nowhere has any mention been made of this or whether the polyurethanes have the same bonding strength. If that be the case, then you are basically connecting the glass cloth to the wood with just multiple coats of clear poly paint which is coating but not bonding to the glass fibers. Granted, this may still be more strength than we need as we all tend to over engineer our models to practically make them indestructible. However, if it's a larger plane that can handle the few extra ounces, I'll use the polyester or epoxy first and get the extra strength. It's more work but worth it in the end. Besides, if properly applied, they don't add a ton of weight. The problem is, most people don't use the right resin and they apply it way too thick.

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

Wow folks. Thank you so much for all the responses. [8D] Campy, your outline was much more than I expected. I sincerely appreciate the time it took to sit down, and thoroughly educate someone new to this process. I have no doubt, that I will implement much of your information in the process of building my P-40E.
I still have a couple of questions though. What is the difference between Polyester Resin (The stuff mentioned by John.), and water based Polyurethane? I am very unclear as to why folks use water based, over oil based polyurethane. Is polyester resin essentially the oil based product?Regards,Chris

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

No polyester resin is not the oil based polyurethane you're talking about. Polyester resin is just that, a catalyzed resin similar in smell to what you smell at the car body shop, although they're most likely using Bondo or some similar body putty. Bondo is basically polyester resin combined with talc to form a thicker, lighter filler. Some brands use micro balloons to make an even lighter filler. These are usually catalyzed with a form of benzoyl peroxide in a tube with a coloring agent. Polyester resin used for fiberglass repairs on cars and boats and such, is a liquid that is usually catalyzed with MEKP (methyl ethyl ketone peroxide). Most times this is more of a laminating resin which leaves just a slight tack for the next layer to stick to (or the Bondo going over the fiberglass to be sanded smoothe). Some people have had success with it but I still find it to be a bit too thick in form to be used in fiberglassing model planes. Since the old K&B resin is no longer available, I'll use Sig's resin which is just like it but you have to buy the catalyst separately. A quart of resin is about $25 from Tower and the resin is about another $2 or so.

Now the difference in the polyurethanes, is like the difference between oil based paint and water based latex paint. Due to the chemicals used and the tightening of controls by the states regarding the volatiles used in oil based products, it's becoming more and more difficult to obtain and I imagine sometime in the not too distant future, will be next to impossible to find or you will need some special permit to purchase and use. The reality of the situation is that I prefer the water based polyurethanes for one over-riding factor...they remain CLEAR whereas most oil based polyurethane will tend to yellow over time. As one of the guys mentioned previously, the Varathane Diamond clear is what I like using but I don't believe it's found in quarts and a gallon of it at Lowe's in my neck of the woods is about $47. Still wayyyy cheaper than polyester or epoxy resin. But like I said in my prior post, I still prefer the polyester for knock 'em dead big scale jobs for the durability. But I am going to use the urethane for my .60 to .90 size birds from now on.

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

the Varathane Diamond is available in Qt and 1/2Pt sizes but you probably have to get it at a paint store where I usually buy it i Qts, I have purchased it at Home depot in the smaller Qt sizes but the larger sizes are for floor finish applications, its main porpose.

in Calif.the VOC Volitile Organic Content,essentally is the resin base and dryers in paint.

water based paint utilizes the same amount of VOC to do a better job,in Ca its 250GPL(grams per litre)the water based paints are using chemicals that are more effective in the regulated VOC range.
oil based paints need a higher VOC to be affectivive, to dry out the resins used in there base, making it harder to make a viable product out of the oil base,with the present restrictions,in our state.
the result is eventually a higher resin content and slower dry times which is part of the reason you see the yellowing from the OBPaints,many painters add rapid evaporating thinners like MEK,or laquer thinner to help with the drying process which tecnically is illegle.
being a contractor in Ca.were required to be on top of the regs,also disposal of product and reducers(thinners)

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

This guy seems like somebody you might want to listen to. Wow. What a great summary!

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

I have always used the monokote to cover my planes and recently tried the fiberglass and waterbased poly method on a TF 60 sized mustang. In my limited experience the poly method has made my mustang much tougher than any monokote covered plane I have had. Needless to say, I'm very happy with the poly method, and for me I consider weight to be extremely important.

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

I started using the water-based Polycrylic about 5-6 yrs ago. I use it over .6 oz. cloth and I only use two coats so I'm not filling the weave with the Poly-C. I have noticed that it toughens up after several months. However, I agree with Campy. The purpose of the glassed finish is to establish a paintable surface, not to make it durable. I use it because its lighter since I stay to models in the 60-80"span. Being easier is a bonus (and a pretty significant one). There's no going back to resins or epoxies for me, except for forming parts.

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

:)

Good topic.

I switched to waterbase finishes because of health issues my wife was having with Epoxy's, Polyester resins and just about anything else that we play with to get a great finish. If it stinks, she was affected.

Prior to waterbase I used, and got use to using dopes, epoxy paints and finishing resins. I was using nothing but silkspan to cover my wings, C/L stunt, which require nitrate dope to shink and other dopes to keep the covering tight. From what I read waterbase polys wouldn't pull the covering tight in the open bay areas. So I had a problem. Either use a iron on film, which is out of the question, or stay with dope which wasn't going to happen.

About 75% of my wings surface is open bay. To cure the problem I bought a roll of light weight doculam and ironed it on just in the open bay area. Very easy to apply. After putting it on I scuffed it with 000 steel wool to give some teeth for the poly. I finished the exposed wood with Minwax sanding sealer, applied the silkspan over the doculam and wood and finshed it with two coats of polycrylic sanding with 320 for the finish. I found a waterbase primer at the auto paint store, spendy but easy to sand.

From there I used AutoAir waterbase finish for cars. Outstanding stuff. WWW.autoaircolors.com Only bad part about the AutoAir is you have to use a automotive clear coat for your final finish. I spray this this in my brothers shop. Using AutoAir you can do a multi-color paint job in a couple of hours. I did 5 color changes in two hours. Start to finish, with clear.

Now for the best part. I was working in my shop the other night and my 21 pound cat Jasper launched from the floor and both front paws landed betweet two open bays of the wings on my newley finished Challenger stunt plane. When I checked the wing I was suprised that there wasn't any damage to the wing. No tears no sagging what so ever. If this had been a just a silkspan finish, well you know what would of happened. This method is much stronger than I though. Also, I did test sample and It was almost impossibe to pull the silkspan off of the doculam.

Well that's about it. I'm sold on this way of finishing.

Rick

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

Wow folks,

Thank you so much. These are wonderfully informative posts! I have to say, I am torn between using a good epoxy finishing resin, like MGS (The less viscous one.), and a hard wb poly over sealer. Now, I know this is going to throw a wrench in the works, but I managed to get my hands on some industrial water based aliphatic polyurethane. Claimed to be used on the hulls of ships and military vehicles. (Macekote 5218) Check out its statistics. Can anyone take a look at this and tell me if I am off base? This look too good to be true? The website is: www.maceco.com

These folks are claiming the following:

Tensile Strength (PSI): 10,000
Sward Hardness: 94 (HARD!!)
Elongation Percentage: <5%
Modulous PSI: N/A (Modulus at 100% elongation, if elongation is less than 100% then Modulus information is Not Applicable (N/A))
Solids%: 35% (+-1%)

Description & Uses
Macekote 5218 is a fully reacted aliphatic polyurethane supplied as a fine particle size dispersion
in water and co-solvent. Upon drying Macekote 5218 produces tough, clear, high gloss, nonbrittle
films that display superior properties when compared to other thermoplastic binders.
Macekote 5218 is one of the hardest urethanes we have to offer and it has excellent chemical,
solvent, alkali and abrasion resistance. Typical end uses include top coatings for wood, plastics
and metal for superior, durable, scuff resistant coatings. Macekote 5218 is a high performance
water based urethane designed to replace traditional solvent based resins. You can enhance the
performance of Macekote 5218 by using our C-70 crosslinker 4% by weight on wet basis.

Key Features
􀂾 Excellent chemical, alkali & stain resistance 􀂾 Outstanding abrasion resistance
􀂾 Tough yet flexible 􀂾 Excellent impact resistance
􀂾 Good weatherabilty 􀂾 Crosslinkable

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

Hey ardrhi, let me know when you order your drum of it and I'll bring a couple gallon cans down to your place in Middletown and buy some off you. [sm=49_49.gif] I'm just up the road in Stone Ridge, about 45 minutes away.

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

I am about ready to fiberglass a .60 warbird. I have .75oz cloth and was going to use epoxy resin. I have half a gallon of West system left over from building a boat and this stuff worked very well on the boat. The waterbase sounds very interesting though and seems to save a lot of weight. I have klasskote epoxy paint to finish with.
Does anyone have a ball park figure for weight using epoxy versus waterbase? I am at 9 lbs unfinished and would like to stay around 10lb finished and painted.

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

My TF 182 - way more surface area than that 60 size warbird - gained only 11oz from bare wood to glassed (with water based PU), primed and painted ( I weighed EVERYTHING and added it up.). I don't know what it would've been had I done the glass with epoxy. I was amazed at how light everything stayed. And at how great a surface for painting it provided.

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

other than a plane that you 'throw' in the car/truck. a weekend beater, in other words, why would you cover all of your hard work with plastic? glass and water poly takes longer but at least you can paint your model.

david

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

I've heard of using nitrate dope (couple of coats); half ounce glass painted down with nitrate; then prime and paint.

Coments?

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

Unfortunately I really don't know much about nitrate dope. I have really only seen it used by one other builder. Don't you have to use silk span? I don't think nitrate dope bonds chemically to glass the way epoxy and polyester resin does.

RE: Oil Poly. vs Water Poly. vs Finishing Resin
 

:eek: Hi Guys,

I am refinishing a Mariner 40 Seaplane flying boat after about 200 plus flights. All plastic covering has been removed and all lightening holes have been filled with lightweight sheet balsa. The entire fuselage has been fiberglassed with 3/4ounce glass and 2 coats of water based Flecto Varathane Diamond Floor Finish. This is my first experience using Varathane and it's a great working product and so much easier, faster than using a 2 step epoxy resin coating.

After reading this discussion here's where I think I may have blown it. I did not seal the balsa with a sealer like Deft Laquer or other. I just brushed on Varathane through fiberglass, lightly sanded and brushed on a second coat of Varathane. Did I blow it? Can I do something to save it? Right now it sure seems as hard as nails.

Also, can I use latex paint, like Krylon Latex spray as my final, FUELPROOF paint finish.

Please advise. Thanks!

The Best Refined Hydrogenated Rosin
 

If you are looking Professional Chemical Manufactutes in China. come to FinJet Chemical Industries website, a professional adhesive supplier offers the best products, Ester of rosin, Resin dispersion Gum rosin, Hydrogenated rosin ester, Glycerol ester of rosin at Afforadable Price.

I have spent almost 47 years in the aerospace composites industry, and I will tell you right now using epoxy resins for finishing purposes in the name of strength is a wast of time. It doesn’t add any more strength to the outside of a model than urethane, but in many cases especially by the new guys, it will come out heavier. Strength and rash proofing comes from multiple plies of glass and epoxy resin. Unfortunately for finishing purposes a single ply of 3/4 glass cloth is the suggested norm over balsa and plywood in an effort to keep the grain in the woods from showing through and to keep it light at the same time, so that single ply doesn’t help with hanger rash and doesn’t do a thing worth mentioning over epoxy VS urethane. I personally use Minwax oil based urethane, and have so for decades, unless of course I am building an all composite airframe or parts. Water based can in fact swell and or warp thin balsa wood so I don’t use it.

Bob