Formar Resin is soluble in ethylene dichloride, xylene or dioxane. It is difficult to maintain a given percentage of solution due to the constant evaporation of the solvent. It is recommended that only small amounts of solution be prepared at a time.
For most purposes a 0.25% solution will suffice for most of the substrate requirements. Several points to keep in mind:
- When a drop is spread on water there is a variation of thickness from the centre out.
- When a slide is dipped in the solution the lower or drain end will tend to show some variation in thickness.
When not in use solutions should be tightly capped. If moisture gets into the solution, holey films will result. A rule of thumb for various thickness films is that 0.1 grams of Formvar in 100mL of solvent will produce films 10nm thick, 0.2g - 20nm, 0.5g - 50nm etc.
To make a 0.25% Formvar solution:
Dissolve .25g Formvar in 100mL high grade ethylene dichloride.
Store solution in a well-stoppered brown glass bottle.