Inside the Factory: Crafting Grout-Free Showers | Syn-Mar

June 30, 2026

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Watch Vice President Derek Hill take you on a behind-the-scenes tour of our Ellington, CT manufacturing facility.

As a plumbing wholesaler or kitchen and bath dealer showroom, your reputation relies on the quality of the products you supply. When contractors are on the job site, they need reliable, easy-to-install grout-free shower systems. At Syn-Mar Products, we have been manufacturing high-quality products right here in Ellington, CT, since 1977.


Unlike competitors who rely on middle-man sales distribution companies, we sell direct to our dealer partners. This direct relationship allows us to provide exact custom sizes, rapid communication, and superior quality control. We are a manufacturer, not a remodeler—which means our focus is entirely on building the best possible product for your showroom to sell.


When you order a custom shower base from us, you aren't just getting a piece of material; you are getting a highly engineered system designed to eliminate job-site headaches. To show you exactly how we do it, let's take a look inside our manufacturing process.

Welcome to Syn-Mar: The Showroom & Office Hub

Syn-Mar Products is a family-owned manufacturer located at 5 Nutmeg Drive in Ellington, Connecticut. Since 1977, we have specialized in grout-free shower systems, custom shower bases, shower wall panels, and seamless vanity tops.


Our showroom, office, and manufacturing facility all operate efficiently under one roof. When visitors enter our showroom, they can explore full-size shower displays featuring our most popular seating options and custom thresholds. Adjacent to the showroom is our office, where our team seamlessly transforms customer purchase orders into manufacturing work orders, coordinating directly with our dealer partners to ensure absolute accuracy before production begins.

The Manufacturing Process: Engineering the Perfect Base

Every product we build begins with a custom mold. In the set-up department, mold stops are positioned and prepared for production based on exact specifications. From there, the mold moves into the spray department, where a specialized gel coat is applied. This permanent outer layer ensures the final product is completely non-porous, waterproof, and highly resistant to stains. 

The Gel Coat: The "Why" Behind Our Durability

Once the mold is perfectly prepped, it moves into our spray department, where a specialized gel coat is applied. We do not take shortcuts here, because this gel coat becomes the permanent outer layer of the finished product.


Why is the gel coat so critical? It is the protective shield that your customers will interact with every single day.


Applying this specific coat provides:


  • A completely non-porous surface


  • Exceptional stain resistance


  • Absolute waterproof protection


  • Long-term durability

The Casting Process: Formulated for Consistency

Once prepped, the base moves to the casting department. We utilize a strict formula for our engineered stone matrix, consisting of approximately 75% stone and 25% polyester resin. The material is hand-cast into the molds to cure. 


It is during this casting and molding process that the three critical components of our custom bases take shape:


1. The Slab: Safe and Perfectly Pitched


Every custom shower base starts with the slab, engineered with a textured, non-slip surface for critical end-user safety. Because the slab is automatically pitched toward the drain, contractors save valuable time on the job site. They simply set the base, knowing the water will flow flawlessly every single time.


2. The Threshold: Customized Entryways


Because residential remodels require unique specifications, we manufacture three distinct threshold profiles:


  • Micro Threshold: 2 inches tall by 3 inches wide.


  • Mid-Height Threshold: 3 inches tall by 4 inches wide.


  • Full-Height Threshold: 4 inches tall by 4 inches wide.


The Micro Threshold is incredibly popular for aging-in-place applications due to its low, accessible entry height. Supplying these custom choices elevates your showroom to a true design resource. 

Diagram of micro, mid-height, and full-height wheelchair thresholds with dimensions for accessible passageways

3. The Flange: Guaranteed Waterproof Integrity



The final critical component is the built-in flange, which goes around the sides of the shower base to provide absolute waterproof integrity for the entire enclosure. Our built-in flange ensures the shower base is completely watertight, safeguarding the homeowner's investment and protecting the contractor's reputation.

Finishing, Inspection, and Seamless Fabrications

The final critical component is the built-in flange, which goes around the sides of the shower base to provide absolute waterproof integrity for the entire enclosure. Our built-in flange ensures the shower base is completely watertight, safeguarding the homeowner's investment and protecting the contractor's reputation.

Finishing, Inspection, and Seamless Fabrications

After curing, products are removed from their molds and transferred to the finishing department. Here, our team removes excess material, sands and polishes the edges, and meticulously inspects the surfaces. Customers can choose between a matte or gloss finish, both of which retain our signature waterproof gel-coated surface. In addition to our engineered stone matrix, our team also fabricates beautiful Corian shower walls and vanity tops. By cutting and finishing this sheet material to exact customer specifications, we provide an expanded selection of design possibilities while delivering the seamless appearance homeowners love. 

Fabricated In-House and Ready for the Job Site

All components are fabricated together using a waterproof adhesive right here in our facility. The entire base is built in-house so that it is completely ready to install the moment it arrives at the job site.

"We don't rely on third-party freight. We deliver everything on our own trucks throughout the Northeast, so your custom grout-free shower systems arrive safely and on time."

-Derek Hill, Vice President, Syn-Mar Products

For Showrooms & Wholesalers: Partner with an experienced manufacturer who values quality, speaks plainly, and stands behind the work. Contact Syn-Mar Products today to expand your showroom's offerings with our premier custom grout-free shower systems and seamless vanity tops.


For Homeowners: Ready to upgrade your bathroom with a beautiful, easy-to-clean, grout-free shower system? We exclusively sell our custom manufactured products through our trusted network of showroom partners. Please utilize our "Find a Dealer" tool on our website to locate a trusted supplier near you!


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