Weighing Pro-seal. Which scale
 

After having built a dozen tanks, Im now building another set and have decided to get more precise than my eye-balls. I have a suspicion that my last set of tanks on my 8 has blisters from possibly not properly weighing/mixing the sealant. Just one possibility of a hundred that has been hashed out in other threads.

So, this time Im gonna weigh it. There are a gazillion kitchen digital scales. I do not know what resolution I need. Is 1gram enough? Seems most go to a gram/.05oz.

A grain of rice weighs ~25mg. Seems I would need resolution to at least that huh?:confused:

Also, last time I read a label, it is supposed to be mixed by volume 10:1. Well how is that ever accomplished? Has to be by weight right? How does the 10:1volume translate to weight?

I have 5 tanks to build on this set of wings and Id preferr to get it right this time. :eek:

Thanks for your help.

I started with a 1g scale and switched to a 0.1g scale. My batches ranged from 5-80 g, and the 1g scale isn't precise enough for the hardener in the smaller batches.

I used a Salter digital kitchen scale that weighs both grams and ounces. It's flat and works great.

What ever one you buy, put it in a large ziplock bag. When you're done, pull out the nice clean scale and give it to you wife to use in the kitchen.

I bought a Walmart kitchen digital food scale, measures in grams and ounces. Most of my proseal loads were from 10 to 80 grams. The mix is 10:1 by weight regardless of what measurement you use.

I really enjoyed the "tare" feature, I put a mixing dish on empty, tared it, loaded "about" the right amount of sealant into that dish, noted the weight, tared it again and loaded 1/10 of the original weight of hardener, and mixed away.

I would not overthink the process. Proseal is relatively forgiving stuff and I doubt improper mixing is the root source of your paint blistering problem. Outdated or worse....improperly stored proseal is a greater threat.

I have only a built a total of 4 leak free RV fuel tanks but in addition to that have repaired a general aviation fuel tank or two and have mixed and applied many hundreds of POUNDS (not ounces) of proseal under the watchful eye of a critical quality control department for extensive use on the taxpayers salt-water combat jets. In the production environment, we mixed proseal and other exotic products using a table top version of the type of scale rigged with sliding weights not unlike the type of scale found in many doctor offices.

For homebuilding purposes, I rely on a good old Royal EX-5 postal scale mixing the proseal 10-1 by WEIGHT as we did on the shop floor...and unless I am missing something, apparently Van's recommends you do the same:

http://www.vansaircraft.com/cgi-bin/...roduct=proseal

I got mine from here:

http://www.micromark.com/DIGITAL-SCA...CITY,8812.html

Great little scale and fairly inexpensive.

I was too cheap to buy a scale. I used some scrap to make a beam scale with one arm 10 times the length of the other one. Gravity hasn't let me down yet.

I bought a very inexpensive digital scale at Harbor Freight Tools, and it worked great. I also used it for weighing epoxy resin, superfil and now paint.

N. Powell
RV-9A
In the process of painting

That is exactly what I used. Plastic cups, the little ones that sit beside the bathroom sink. I made up about 3 ounces at a shot for one rib at a time.

mail scale