Instructions for use

Fig. 9a

5a. COVERING SHEETED SURFACES WITH STYRENE FOAM

CORES

(Fig. 9a, 9b)

Superheated steam is used in the production of polystyrene foam cores; so

many foam wings often contain relatively high levels of residual moisture. At

ordinary room temperature a stable microclimate stabilizes inside the core

retaining the moisture. That is the reason why moisture even after long

periods hardly evaporates from foam cores. The heat applied during the

covering process draws moisture from the cores and can produce bubbles in

the film. Sometimes during bubbling, the covering can be ripped from the

wooden surface leaving wood fibres attached to the covering. As a result you

may get "permanent wrinkles" where it becomes impossible to iron the

covering back onto the surface of the wood. To avoid this problem we

recommend you apply a thin layer of ORACOVER - iron-on adhesive (ref.

no. 0960) as a moisture barrier and let it dry overnight. Note: it is important to

apply a thin layer so that the solvent in the adhesive does not damage the

foam core. Once this barrier has cured, you can cover the model.

Set your covering iron to low (90 °C) tacking the ORACOVER from centre,

as we did in Fig. 6 and 13. Tack the entire surface with low heat; then again

repeat the same procedure with medium heat (120 -130 °C) as in step 8. Keep

your iron flat on the surface so all of the ORACOVER is tightly bonded to

the surface. For the second and final shrinkage you can also use a paint-

stripping gun, see step 9. In doing so the covering must be firmly pressed onto

the surface with a soft cloth (or kitchen roll), or better still, with the

ORACOVER -felt blade (ref. no. 0915). Do not use too excessive heat, as

you may cause damage to the foam core (fig. 9a, 9b).

6. COVERING THE WING TIP (Fig. 11a, b, c, d)

Set the iron to high (150 - 200 °C) for difficult curves. Pull and stretch the

ORACOVER around the wing tip while heating it with the iron, tacking the

material in place. (see Fig. 8). As the ORACOVER cools, maintain the

tension to allow the adhesive to grip.

DO NOT attempt to eliminate all wrinkles at

(fig. 11a, b, c, d).

Note that ORACOVER can be ironed onto the structure and then heated

and removed without damage to the material as often as needed.

this stage. If there are deep folds

along the tip, then heat the ORACOVER and release the folds, and re-

stretch until reasonably smooth. You can easily do these jobs with a heat g

Fig. 11a-d Covering of the wing tip

Fig. 10a Trim off surplus

Fig. 10b Complete bonding

Fig. 9b Final shrinking

Fig. 9 / 9a Gradually work around

curves