Create a perfect fiberglass finish

Jun 27, 2012 13 Comments by

Here’s another how-to from veteran builder Rick Michelena. Enjoy!

Do you have the desire to build a warbird or other scale project but desire something more than an iron-on finish? Are you unsure of the steps required in the process of finishing a radio-controlled airplane in fiberglass and paint? This article will give you the knowledge required to finish any project. In fact, by following these steps, your models will look better than 95% of the models appearing at your local club.

Before we begin, I would like to mention that I do not compete in Top Gun events nor spend the necessary time required to build these master- pieces. I build my models to fly and to last. As those who know me will attest, my models have each accumulated thousands of flights over 25+ years in service. My motto is simple: No hangar queens!

However, if you desire to learn how to fiberglass and paint, these tips will help you go the “extra mile.” With that said, let’s discuss the necessary steps involved in producing an excellent finish on your next project.

This is the wing of my giant scale F8F Bearcat. It is a foam core covered in 3/32″ balsa skins and has been sanded with #100 sandpaper.

Lightweight spackling is the secret for creating a perfectly level finish. It is available at both Lowes and Home Depot. It is lightweight and will fill every imperfection in your balsa skins.

After I blow all the sanding dust off the wing, I use a spray bottle and water to slightly dampen the balsa skin. With a plastic “Bondo” spreader, I spread the spackling all over the wing area. If it becomes dry, mist some water on it to smooth it out. I allow this to dry overnight.

I do the same procedure with all the flight controls.

This is the horizontal stabilizer. Please notice the darker area where I used fiberglass tape to attach it to the fuselage.

I then skimmed the lightweight spackling over all the surface. This is an important step in leveling any surface and is an essential step in paint preparation.

A Black & Decker Mouse sander will save both time and energy. I begin with #100 paper and use a block-sanding motion (sanding back and forth in an “X” pattern) to level the surface where the fiberglass cloth will lie.

Remove the majority of the lightweight spackling, and this surface is now perfectly level in preparation for the next procedure, which is fiberglassing. Don’t let this next step scare you. The process is easier than you think.


Here are the simple items needed to produce a fiber-glass finish that will last for many years. You will need the following: 3/4 ounce fiber-glass cloth, 90% isopropyl alcohol, Z-Poxy finishing resin, mixing cups, stir stick, scissors, and sponges cut in small squares.  We’ll continue with the rest of this project next week — stay tuned!


Align RC USA, How-tos

About the author

Model Airplane News Executive editor. About me: I’m a publishing professional who has a passion for aviation and RC, and I love creating issues, books and a website that help RC pilots to enjoy this sport even more. I admire scale aircraft and enjoy the convenience of flying smaller electrics.

13 Responses to “Create a perfect fiberglass finish”

  1. david pearce says:

    Hey, let’s get on with this, I am using this procedure to restore my full scale Pipeer Cub. If it is as good as you say, then I am a chinch for the best finish award at Oshkosh this year. thanks. d

  2. Terry Solesbee says:

    In spreading the resin I have had great success using playing cards which can scrape the excess resin out of one spot to spread to a spot that needs it,no waist ! I did an 85″P51 wing with 4 oz’s (less flying surfaces) that’s top and bottom,don’t let it soak in.Use one oz at a time you only need enough to make it stick.Check out my P51 “RED DOG XII” on youtube. It took 2nd place at scale squadron for Best prop war bird.

  3. Terry Solesbee says:

    Is a Piper cub Fabric covered? If so it wont work.

  4. David says:

    Great article, thanks!!! Am contemplating building a Ziroli 101 inch B-25 or maybe Ziroli Black Widow. Looking forward to part 2.

  5. Joe B. says:

    An alternitive to the Pacer Z-Poxy Finishing Resin and I find to be an absolute dream to work with is Min-Wax brand Satin PolyAcrilic. Brushes on with foam brush, cleans up with warm water and soap, dries in 30 min or so. it will take several more coats than the finishing resin to fill the weave but it is odorless and doesnt add to the weight much at all since its waterbased and most of it evaporates away.

  6. Jonathan says:

    I hate the “waiting”!! Oh well, I guess it gives me reason to check back!

    Great article and looking forward to the rest of the build.

  7. Nick says:

    In second the minwax poly. The only trick I found was to use sanding sealer first to prevent warping wood and to let the sealer “gas out” a week or so before applying minwax. By far the lightest combo I have found as the poly just evaporates ( quick too)

  8. AnonymousGarth Rockey says:

    Is it next week yet?

  9. Robert Lundstrom says:

    Is there a place to go (or will there be) to see the whole article? I am worried about losng all of this info or not being able to find it all. Great article! I would like to be able to save the info as a link or be able to download it.

    • Debra Cleghorn says:

      Part 3 is coming next week and all three parts will be available for the foreseeable future, but due to the changing nature of the web, I recommend that you print each article section if you want to keep it for posterity.

  10. Rick Michelena says:

    Hey guys,

    I’m glad you enjoy the information. I will agree that Min-Wax can be used to adhere fiberglass cloth. However, Z-poxy is still harder. Before Pacer products came out, I used the old Hobby Poxy 45 minute and thinned it with denatured alcohol. This was far superior to the old K&B polyester resin technique. Good luck…these steps, and a little patience, will yeild a great result.

    • Joe B. says:

      I have never used it because I like the polyacrylic, but doesn’t the epoxy get waxey when drying. I believe I have read that some where.

  11. odell says:

    couldnt find pacer products w/o mail order so used local boat shop for resin.followed directions and added alcohol not sure if was 3/4 oz. cloth but resin was still tacky a week later and some of the cloth didnt take.was afraid to add more resin so what went wrong any ideas.

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