Building with Dollar Tree foam - Part 4 - Paper removal and sealing lessons learned

Hi Everyone -

As mentioned in part 3 of this series of articles, I wanted to cover some lessons learned on the removal of paper from DTF and then sealing (other than Minwax which I covered in part 2) for maximum strength and durability.

With the paper left on, DTF is actually quite strong even before reinforcing, but is very heavy compared to Depron and MPF. Additionally, the paper can become heavy and peel off if it comes in contact with water (why it is good to treat it with Minwax).  So it is a challenge to remove as much of the paper as possible while still retaining strength in critical areas and not having the paper peel off over time.

I should note that since first writing this article, I have also started using the Dollar Tree foam with the black paper on it based on a tip from Peter (homey666 from the RC Powers forum). The paper on this foam is much more consistently easy to remove compared to the foam board with white paper. For parts like the fuselage and KF airfoils, I will use this foam, I still use the white paper foam for parts that I will paint.

To score the paper along the areas where I wanted to remove it, I used a new, sharp blade in my #11 Exacto knife like this one.  I like this knife for this process as it is lightweight and easier to use a very light touch than other knives I like to use.

Normally the white paper will peel off relatively easily, but there are times when it does not want to come off cleanly either because of how it was processed or if I was a bit "glue happy" when putting the plans on the foam before cutting them out.  Here is an example of what can sometimes happen.

Normally, if I apply some of this solution I get from the Dollar Store, within about 30 seconds the paper will peel off quickly, but even after applying it, it requires some gently scraping to the get the paper off.

I apply the alcohol solution with one of these foam brushes, another thing I can get from the dollar store, this also helps me control how much of the solution goes onto the foam/paper along areas where I have trimmed the paper off the foam.

Normally once the paper has been saturated with the alcohol solution for about 30 seconds, the paper can be lifted off quite easily.  I know this picture shows a different part of the plane than above, but hopefully you get the idea😉

Sometimes even this won't fully remove the paper, so a little more alcohol solution can be applied and then gently rub the paper off in bits.  This is a bit messy, so best to do over your garbage can or you have all kinds of little bits of paper everywhere😒

I then let any areas that are trimmed dry completely before applying any glue.  I use this glue that I can get at the Dollar Tree that is identical to Bob Smith Industries Foam Cure. 

I spread a very thin bead along any edges of the paper (very important to do this before treating with Minwax), then spread it very thin with some scrap foam to press it into the edge of the paper.  Also, when using the razor knife to remove paper on both sides like on this elevon for example, the foam is very thin and the bare part can break off easily.  This glue dries very strong like epoxy and is light and sandable, so I do all the sealing before sanding anything.

It is important to do this rather tedious treatment along the edges of the paper as the Minwax will waterproof the paper, but it will not glue down the edges to keep them from peeling or from allowing any moisture to get between the foam and paper where the paper has been trimmed.

In my next blog post, although I no longer have this plane in my "hangar", I will go back in time a bit and share my thoughts after initially flying the first all DTF plane I built and flew😊

Park Jet noise...the "other" sound of freedom😎

Cheers,

Scott