Hip Pocket Builders' Forum

Indoor Free Flight Forum => General Discussion => Topic started by: KingDelta5 on March 01, 2019, 10:51:43 PM

Title: Would Minwax polyurethane work like Minwax Spar Urethane
Post by: KingDelta5 on March 01, 2019, 10:51:43 PM
Hello :)
I want use the wipe on wipe off method to use as a dope / coating to cover my balsa gliders !
Trouble is I can find no Minwax helmsman spare urethane anywhere !
I do have some Minwax Fast-Drying polyurethane !

Has anyone used this ????
anyone know what the differences in these products are ????

Seems to me either might work

I just want a very lite coat :)

any comments or thoughts be greatly appreciated
Thank You

Title: Re: Would Minwax polyurethane work like Minwax Spar Urethane
Post by: kittyfritters on March 02, 2019, 02:07:32 PM
I was looking for a dope substitute since my wife is very allergic to nitrate dope.  I've been using Krylon #1305 artists fixative for most of my builds but when I need something more waterproof I have been using water-based polyurethane diluted with water or rubbing alcohol to the consistency where I can airbrush it.  I have also mixed talc into it to make a sanding sealer.  Since I live in the confines of the South Coast Air Quality Management District most of the polyurethane products available are water-based.  I don't know if the Minwax product you have is water based or solvent based.

I have also used Armstrong Shine Keeper, a commercial, acrylic floor finish, also diluted both brushed and airbrushed.  It's quite durable and about $15 for a half gallon, but takes a little practice to get the right dilution to get a good finish with it.

Hope this helps!


Title: Re: Would Minwax polyurethane work like Minwax Spar Urethane
Post by: KingDelta5 on March 02, 2019, 03:26:04 PM
Thank you for the reply
I did find the Minwax Helmsman Spar Urethane I was looking for
I bought a quart
Seems I ought to have plenty for quite a while into the future :)
The climate here is very humid much of the time
If you do nothing to protect bare balsa
It will actually become soggy
I suppose in the age we live in now
we have to experiment as to we can find and can get to work
butyrate dope is not easily available here

Seems nothing to do with model building is healthy
I seem to have acquired a allergy to balsa dust
I also get very sick from cyanoacrylate glue !

I never had a problem with dope !
But am sure
The name Dope was no accident
certainly the fumes must be dangerous

Thank you much for your info and reply

cheerio :)

Title: Re: Would Minwax polyurethane work like Minwax Spar Urethane
Post by: kittyfritters on March 03, 2019, 12:46:43 AM
Working with modeling materials does require some caution.  The original use for what we refer to as "dope" was as coffin varnish!  If you are building gliders, electric or rubber powered models butyrate dope is not an issue since fuelproofing is not an issue.  However, I have seen some larger IC engined R/C ships painted, successfully, with house paint.

I suppose that you already wear a particle mask when sanding balsa.  Here in California we have to include a "Proposition 65" warning in kits to inform buyers that "wood dust is a carcinogen" despite the fact that the only wood dust known to be a carcinogen is Western Red Cedar.  While balsa dust is not known to be a carcinogen (it has been tested) it can cause severe allergies.  Building with foam is not the answer since you can get more severe problems from sanding rigid foams.  Masks when sanding are good practice.

I have had cyanoacrylate poisoning a couple of times and it's not pleasant.  This can be avoided by not bending closely over your work, having adequate ventilation, and immediately hitting each joint with a drop of the accelerator (kicker) made for that brand of glue from a dribble bottle.  The kicker usually comes in a spray bottle. but DO NOT spray it.  The kicker can be worse than the glue.  Transfer it to a dribble bottle and apply it a drop at a time.  By setting the glue immediately you prevent the fumes from spreading from the joint.  I have not had a reaction to cyanoacrylate since I was shown this technique and I use it almost every day. 

Another, gluing in a hurry, technique is to use white glue. or TiteBond I,II, or III, glue up your assembly and put it in the microwave for a minute.  This works extremely well, BUT if you do this and forget to take out all the pins you will have a fire. (See picture.)

If you think there are problems with modeling materials you should have taken art classes back in the 50s.  At the time, no one told us about how poisonous all of that stuff was!  It wasn't until the 60s that we found out.

Keep 'Em Flying!


Title: Re: Would Minwax polyurethane work like Minwax Spar Urethane
Post by: lincoln on March 03, 2019, 02:30:20 AM
I understand that much of the shaping of balsa gliders can be done with a sharp plane instead of sanding. That ought to keep the dust down.

Foam can be wet sanded.