Chapter 25 - Section 1



While I am waiting for the engine mount and engine to show up, I decided to start on some finishing tasks. It's been told (among Cozy builders) that this finishing chapter is long and tedious. It is advisable to make some progress a bit at a time between the rest of the fabrication tasks. I took the time and read all archives and web sites related to finishing before taking the first step. I highly recommend it because there is a lot to learn in this process.


The various sections in this Chapter are in the form of information and instructions, therefore, the arrangement of this chapter will deviate from the Plan sections and it will be more towards my progress instead.    


West System vs. Aeroepoxy Light

My first decision was on the type of fillers to use. I narrowed it down to the West System (105/206) as recommended by Plan and the Aeroepoxy Light.  I bought starter kits for both systems and tried them out on a couple pieces of scrap glass surfaces - before starting the major undertaking. Here's my limited experience with them:


West System

Preparing for the West System is more in tune with our normal mixing of the resin/hardener and then adding a certain amount of micro for the desirable consistency with the following characteristics:

- It is easier to mix than the Aeroepoxy Light;

- You must remember the mixing ratio and stick to it, otherwise you will end up with spotty hardness for sanding;

- It is more difficult to spread than Aeroepoxy Light, curing up behind the putty knife, tearing (lifting off) from glass surface;

- Leaving sizable pin holes;

- Can start sanding (cheese grating) with 2 - 3 hours curing time;

- Cheese grating is rather easy to remove excess filler;


Aeroepoxy Light      

Aeroepoxy Light System comes in paste form, you just mix the 2 pastes (2:1) and its ready for use:

- It is harder to mix (paste w/paste) and its hard to tell if it is mixed well because both pastes are opaque (brown & white);

- Spreads like peanut butter with no visible pin holes;

- Requires 12 hours curing time before sanding;

- Very easy to sand;

- Clogs up sand paper easily, with little sanding.


After a few trials, I decided to make my first step with the West system because I really like the ease of the 'cheese grating' part. The rest of the sanding was not bad either - except dust gets everywhere. The part I do not like is that I tend to get pin holes and mouse bites on the finished surface. I have to learn how to fix them.


Round 1 to Round ?

I have heard about the laborious filling and sanding process long before I reach Chapter 25. Now that I am here, I am prepared, at least mentally. The one thing nobody mentioned was how many rounds of filling/sanding & priming you might have to go through. I thought if I do it right, one pass should do it before paint. I don't know about others, I am at my third round! That means I have sanded down and primed the entire plane 3 times, so far! Hopefully it will be my last before paint. So plan on more than one round of filling, sanding and priming...unless you try Guide Coat.


Guide Coat

I have talked to many Cozy builders and a couple professional airplane painters before my filling and sanding process. Several of them will tell you its a waste of time and that you are adding 'junk' under your primer and paint. Some will swear by the light and water methods - and they do have beautiful airplanes. I did not try the guide coat approach until my third round - because all these little low spots and bumps keep showing up after a nice shinny coat of primer. After my second round, I decided try guide coat to help identify all the low and high spots. I just cannot imagine anyone can find those little flaws by reflective lighting approach - certainly no way for me! I am a believer of Guide Coat. You can see some of my experience in the following chapters.


Dust Mask

If you think you have generated lots of dust in the prior Chapters, think again! I have been using various N95 disposal masks, including the ones with exhale vents. As most people, I tend to over use them and did not dispose of them soon enough. The masks gets stretched, sagged and allows unwanted dust in - just not good for our lungs. In addition, the exhale vents tends to fogged up my glasses.


I finally decided on a more serious search on dust masks. I wanted one that seals my nose well, keep all the darn dusts out, light weight, and does not fog up my glasses. I finally found one made by 3M P100 Half face Mold Remediation and Lead Abatement Respirator (PN# 6297PA1-A). Its light weight and when I remove the mask after a long day of sanding, there is no dust residue on my face that is inside the mask. I found mine at Home Depot.