3M77/naptha dry covering, was : New LPP

From: Mark F1diddler <f1diddler_at_yahoo.com>
Date: Fri, 02 Apr 2010 14:23:00 -0000

--- In Indoor_Construction_at_yahoogroups.com, "Bill Gowen" <wdgowen@...> wrote:
d> Mark has given me more detail about how to adjust the mixture but I'll leave that to him to explain. >>


I thought Bill once nailed the mixture at 12:1? That sounds about right. I used to sweat almost each milligram in adhesive weight because I would be chasing weight at that point in the build. These days I'm not sweating weight too much (talking F1d) but understand why it's needed sometimes. Anyhow, my mixing now is just by color--slightly cloudy, translucent mixture, not too milky. This obviously not too useful an explanation, so you may want to try Don Slu's prescription. Put a scrap of balsa stick in corner of film on covering frame, apply adhesive mix, and see if you can pull stick off after dry (30 minutes or so.) If you can pull stick off with some resistance, and not tear film, that's what you want for lightweight indoor. If it's stuck hard, leave it alone, thin the mix, repeat. Don't depend on a correct mixture to stay that way more than one day (evaporation.)

<<You can always check the results of whatever method you use by careful weighing before and after covering.>>

Not so easy to separate the exact film weight from the adhesive weight. But easy enough to get an overall covering job weight.

<<I took covering lessons from the Master...Look in the Files section under "How to Cover" and you will see Mark's method listed first followed by my old method>>

Thanks, Bill, didn't know I was a master, and I certainly didn't invent the dry covering concept. I did combine many good ideas I had seen over years. For example, Coslick's two rail covering jig solved the diagonal wrinkle problem, but involved installing crossed turnbuckles on wire. The vaseline film hold (scoot, nudge film on the rails) accomplishes same thing (no turnbuckles.)
Mark F1diddler
(I'll add drawing of film-holder jig to Files article, hopefully soon.)
Received on Fri Apr 02 2010 - 07:27:42 CEST