Filler and Fairing Materials for Foam Before PMF

[Chefsonora]

So I've gathered all of my odds and ends of materials that I think ill need to fill my small gaps and fair/smooth the transitions. I've got the usual array of sheet rock tools and consumables (including the sticky fiberglass seam tape, scrapers and spreaders) and then I got to thinking about economical gap goop. I figured straight joint compound probably wouldn't bond well enough, or be flexible enough..... then I got to wondering if anyone has tried adding something like latex paint to the joint compound to increase it's pliability and bonding potential? My research talked about adding latex paint to be able to build the compound up for additional texture, but no references for camper building. Thoughts?

 

[QueticoBill]

White glue mixed into joint compound works for scenery, but not sure If use joint compound on the exterior of a teardrop in any case. I hope others can help.

 

[KCStudly]

Pretty sure light weight ceiling spackle has latex in it, just be damn sure you're going to use PMF, and not change your mind to use epoxy/glass.

 

[Pmullen503]

Adding latex makes sanding difficult, so you want to apply it and smooth it so minimal sanding is required. Don't just apply gobs and assume you can sand it flush.

If the gaps are small (less than 1/8") don't worry, it'll be OK.

If you have larger gaps, I would recommend cutting strips of foam and glue them into the gaps (keep the glue off the surface) and sand them flush.

Foam is soft and it's difficult to sand a harder filler flush without sanding the surrounding foam.

 

[Chefsonora]

I'm just trying to explore options because I'm going to need a fair amount of fairing....because of my curvy design

 

[ghcoe]

Dap Light Weight Spackle. I fill all my gaps and fair the surface with it. It sands similar to XPS foam.

Pro tip: If you are fairing up a area and you find that you are still too low, but got everything already smooth, paint the area first and then add the additional spackle layer. The paint will not sand easily and keeps you from over sanding in that area again. Plus, it will add more strength to the layers of filler.

 

[Chefsonora]

Good tip, I was trying to figure out a method that wouldn't be a total pita to smooth but resist the flex