epoxy? RTV? resin? environtex? Ca? Matte medium?

[Anonymous]

epoxy? RTV? resin? environtex? Ca? Matte medium? I see these terms used quite often but I have no clue what they mean...[?]

[tstage]

Ted,

Welcome to the forum! Good to have you aboard! [:)]

I'll try to help with with some of your questions:

Epoxy = Usually, but not always, a 2-part adhesive for bonding two materials together. You usually mix together each part in equal amounts. Usuable time is about 5 minutes before the epoxy begins to stiffen or set up. Dries hard in about an hour. Makes a VERY strong bond between pieces. One-part epoxies are also available and come in a variety of curing times - i.e. shorter or longer. They work well for parts that need to be repositioned after you stick them together. (I use this to hold down the weighted bar in my box cars and hoppers.) Caution: Use good ventilation when using this product.

RTV = A silicone adhesive made by Dow Corning (or used to be) that cures in air with acetic acid*. Basically used for caulking. (*If you take a whiff of it before it cures, it will smell something like vinegar.) Plus: No need to worry about fumes.

Spread thinnly, RTV can be used to hold down roadbed to either plywood or foam table top, or track to the roadbed without attacking the foam. Makes a good, strong bond but it can be peeled up with a good puddy knife if either track or roadbed need to be removed or replaced, without damaging the table top.

Resin = Used in making highly detailed, top-quality models, such as rolling stock. Although much less expensive than brass, resin tends to be brittle so models are far more delicate and won't stand up to an inadvertant "bump" that an equally detailed brass model could without damage.

Enviontex = An environmentally safe product used to simulate water on a layout

CA = cyanoacrylic adhesive, sometimes referred to as "Super Glue" or "Crazy Glue". It's a one-part glue that instanteously adheres two objects together. (Key word: instantaneous) As opposed to epoxy, not much adjustment time for adjusting or repositioning parts AFTER you stick them together. Caution: Use good ventilation when using this product.

Matte medium = I'm probably wrong but I believe it's the spray adhesive that comes in a can? 3M makes a version of this. Great for adhering photos to card stock. Caution: Use good ventilation when using this product.

Ted, I hope that helps. Make sure you don't let another 2-1/2 years go by before asking your second question...[:D]

Tom

[JohnT14808]

Welcome to the forum, Ted.

I agree with all that tstage noted, exccept the final part about Matte medium. Matte medium is a water based adhesive that can be applied with a brush, eyedropper or mist sprayer, depending on the task you are working on. Usually used to hold foliage to tree branches ( use a sprayer), or to glue down ballast for your track ( eyedropper ) or in an undiluted form, you can glue paper or cardboard together, but you may want to use white glue or some other product for that.
You can order matte medium from Scenic Express or Woodland Scenics in undiluted or diluted form.

[tstage]

Thanks, John! [:)] I wasn't completely sure on that one. I take it then that Hob-E-Tac would be considered Matte medium?...

Tom

[dehusman]

RTV rubber (room temperature vulcanizing) is a type of rubber used for making molds that can be used for casting with resin, epoxy and plaster. There are many different brands. The stuff that cures with acetic acid is more of a latex rubber.

What they are describing to hold down roadbed is not RTV but latex adhesive caulk. There is also silicone adhesive caulk but it is virtually impossible to remove once its put down. Great if you are caulking windows, not so good if you are moving a switch.

Resin also is not necesarily brittle anymore. The polyester resins feel and handle much like plastic except that you have to glue them with CA or epoxy. Actually, unless filled with a binder epoxy resin is much more brittle. I cast my own cars out of resin and they are just as tough as the styrene models.

Matte medium is basically clear latex varnish with a flat (matte) finish. It is used as a protective coating and base coat by artists. It is a fairly thick white liquid that dries clear and being latex, its slightly "rubbery" which means it is not as brittle and hard as white glue when used with scenery materials. It is commonly used as a fixative for ballast and ground foam. Another related product is gloss meduim that has a glossy finish. It can give a shiny appearance to surfaces that are supposed to be wet and can be used to gloss coat lakes and rivers.

Dave H.

[gmpullman]

Personally, I haven't found much use for silicone RTV on a layout. Some of the silicone compounds resist paint. however, I do recall a use for silicone RTV to mount light poles, signals and sign posts. Drill a slightly larger mounting hole, partially fill it with the RTV and stick your pole centered in the hole. After it cures you have a "flexible" mount that can withstand an occasional bump without snapping off the pole... otherwise just use RTV to caulk the tub surround...

[bogp40]

QUOTE: Originally posted by gmpullman

Personally, I haven't found much use for silicone RTV on a layout. Some of the silicone compounds resist paint. however, I do recall a use for silicone RTV to mount light poles, signals and sign posts. Drill a slightly larger mounting hole, partially fill it with the RTV and stick your pole centered in the hole. After it cures you have a "flexible" mount that can withstand an occasional bump without snapping off the pole... otherwise just use RTV to caulk the tub surround...

My only use for RTV, so far, is for mounting can motors when repowering. I don't trust the doublesided tape recommended or supplied. All my repowered Athearns using Proto Power West chassis have had the motors repositioned and secured with RTV.
Bob K.