Making a Brush-On Mold Using Mold Max® Stroke® Silicone Rubber

Making a Brush-On Mold Using Mold Max® Stroke® Silicone Rubber

Mold Max® Stroke® is a brushable tin silicone rubber that self-thickens for making fast brush-on molds of almost any model. Properly applied, it will hold a vertical surface and will reproduce the finest detail. Mixed 100A:10B by weight, rubber quickly develops thixotropy and can be applied with a brush or spatula. Working time is 20 minutes, re-coat time is 45 minutes and cure time after the final layer has been applied is 16 hours at room temperature.

Mold Max® Stroke® silicone will not stick to most surfaces and will cure with negligible shrinkage to astrong, flexible Shore 30A rubber. 4 thin layers is all that is necessary to make a strong and durable production mold for casting wax, gypsum, concrete or resins (urethane, polyester, etc.). Applications include reproducing sculpture, architectural restoration, making candle molds, casting pewter, etc.

Distinct Material Benefits:
• Save money! – use less material than block molds
• Relative convenience – two-part system eliminates need for third component thixotropic additive
• Less expensive than platinum-cured systems
• Not nearly as susceptible to cure inhibition – will cure against sealed sulfur clay original
• Not heat sensitive – full work time in warm environment

1 - The original relief sculpture has fine detail and some undercuts.	2 - Choosing the right materials: Mold Max® Stroke® is a brushable tin-catalyzed silicone perfect for applying to vertical or even inverted surfaces.	3 - Safety First!: Wear eye protection when working with mold making materials.
4 - Safety First!: Wear gloves when working with mold making materials.	5 - Begin by spraying a thorough coat of Ease Release® 200 release agent over the original model.	6 - Mold Max® Stroke® is measure 100 Parts A to 10 Parts B by weight. Begin by measuring out the A component.
7 - Mold Max® Stroke® is measured 100 Parts A to 10 Parts B by weight. Add an appropriate amount of the B component.	8 - Thoroughly mix Parts A and B together. Be sure to scrape the sides and bottom of the container several times.	9 - Mold Max® Stroke® is white in color. The original model is also white. Adding some Silc-Pig® Red silicone pigment to the Stroke® will ensure thorough coverage when the rubber is applied.
10 - Thoroughly mix Silc-Pig® Red into the silicone.	11 - Continue mixing in pigment until no color striations are present. The silicone is now solid pink in color.	12 - Begin applying Mold Max® Stroke® to the original.
13 - It is important that the first layer of a brush-on mold be applied in a thin coat. This helps eliminate the possibility of entrapping air bubbles.	14 - Be sure to look at the model from all angles. This will ensure thorough coverage. Brush silicone around the outside of the piece to create a flange.	15 - After the first layer has partially cured (approximately 45 minutes), mix and apply a second layer of Mold Max® Stroke®. No pigment is added as the white rubber contrasts well with the first layer.
16 - Cover the entire model and continue building the flange.	17 - This layer can be applied slightly thicker than the first. There will be a total of four layers.	18 - Mold Max® silicone rubber keys are cast into plastic ice cube trays. Mold Maker's Tip: Mold keys are used to help align a rubber mold into a rigid support shell.
19 - Sil-Poxy® silicone adhesive can be used to adhere the keys to Mold Max® Stroke®.	20 - Once the second layer has partially cured (approximately 45 minutes), adhere keys to the outer edges of the mold.	21 - Allow Sil-Poxy® to fully cure (12 minutes) before applying the next layer of Mold Max® Stroke®.
22 - Mix a batch of Mold Max® Stroke® with Silc-Pig® pigment added. Add Thi-Vex® silicone thickener to thicken the batch.	23 - Thickened rubber can be used to quickly fill in undercuts and smooth sharp edges.	24 - Fill in undercuts and smooth sharp edges of the original.
25 - Allow thickened layer to partially cure for 45 minutes before applying the next layer.	26 - Mix and apply another layer with pigment added. Do not added thickener.	27 - Completely cover model and build flange. Allow layer to partially cure for 45 minutes.
28 - Mix and apply a fourth layer of Mold Max® Stroke® with no pigment added.	29 - Cover entire model and flange to complete the fourth layer. The rubber mold should be approximately 3/8'' (1 cm) thick. Allow entire Mold Max® Stroke® mold to fully cure (16 hours).	30 - Using a sharp razor knife, cut excess silicone from the outer edge of the mold. Create straight edges and square off all corners.
31 - Spray the rubber mold and surrounding surface with Ease Release® 200 to separate the support shell from the mold. In some cases, Smooth-On's Sonite® Wax may be necessary to release surrounding surfaces from the support shell.	32 - Creating the rigid support shell: Smooth-On's Plasti-Paste® is a trowelable urethane resin designed to be used for support shells. It is mixed 1 Part A (liquid) to 2 Parts B (paste).	33 - Combine 1A:2B and mix thoroughly.
34 - Mix Plasti-Paste® thoroughly. Be sure to scrape the sides and bottom of mixing container. Mix until there are no color striations.	35 - Apply Plasti-Paste® over cured Mold Max® Stroke®.	36 - Cover the entire mold with Plasti-Paste®. Important: Plasti-Paste® has a working time of 8-10 minutes. Do not mix more material than can be applied in this amount of time.
37 - Mix and apply more Plasti-Paste® as needed. Be sure to apply material beyond the edge of the silicone mold.	38 - Apply at least 3/8'' (1 cm) thickness, making sure rubber mold is thoroughly covered. Large molds may require added thickness for support shell stability.	39 - Wooden blocks are attached to the support shell with additional Plasti-Paste®. These blocks will help level the mold during casting and allow for easier handling.
40 - Once all Plasti-Paste® has fully cured (approximately 90 minutes), carefully remove the support shell from wall.	41 - Plasti-Paste® is strong, durable and lightweight.	42 - Edges of the support shell can be sharp. Sand Plasti-Paste® to make handling safer and easier.
43 - Peel Mold Max® Stroke® mold away from the original piece.	44 - Seat the rubber mold into the support shell. The mold keys added in the previous step will make aligning the mold with the shell very easy.	45 - Once seated, check the level across different axes.
46 - Casting a lightweight reproduction: duoMatrix® NEO is a polymer modified gypsum system that is perfect for casting strong yet lightweight architectural elements. It is mixed 100 Parts A (powder) to 50 Parts B (liquid).	47 - Using a drill mixer, combine powder with liquid.	48 - Mix thoroughly, pausing occasionally to scrape the sides and bottom of container.
49 - Pour mixture into the mold. This first batch will be used to make a ''gel coat'' on the surface of the mold.	50 - Brush the gel coat over the surface of the mold to create a thin layer of duoMatrix® NEO.	51 - Smooth-On's Matrix® Chopped Glass is the perfect chopped fiberglass for layup applications using Matrix products. It adds great strength and durability to a NEO casting.
52 - Matrix® Chopped Glass is added as a percentage to the system. For best results, 6% chopped fiber by weight should be added to the mix.	53 - Soaked glass fiber can be laid up by hand behind the first coat of NEO.	54 - Push chopped glass mixture into deep areas of mold.
55 - Thorough coverage will give the piece the greatest strength and durability.	56 - Mix and apply a second batch of duoMatrix® NEO with no fiber added.	57 - Brush Matrix® over the back of the entire casting.
58 - Once the casting has fully cured (about 1 hour) carefully turn the mold upside down and remove the support shell.	59 - Peel back the Mold Max® Stroke® silicone rubber mold from the Matrix casting..	60 - Mold Max® Stroke® reflects perfect detail captured from the original model. duoMatrix® NEO makes for a perfect casting.
61 - NEO casting is thin, strong and lightweight.	62 - The perfect reproduction: A Mold Max® Stroke® mold can be used many times to reproduce exact replicas of just about any original model.