Frequently Ask Questions


  • What is Solvent Cement?
  • How does it Work?
  • What Plastics can be Solvent Welded?
  • What is Pipe Cleaner
  • What is Primer and is it necessary?
  • What are the most commonly used cements?
  • How does solvent welding work?
  • How long will it take to set?
  • How long does the cure take?
  • Why are there so many kinds of cement?
  • How do I choose an applicator for a job?
  • The cement on the outside of the joint is still soft, is this glue still working?
  • This cement has become thick/lumpy/dry, what can I do?
  • My cement froze, what can I do?
  • I spilled purple primer, what can I do?
  • What problems are reported in the field?
  • What are the safe precautions for working with these products?
  • Is solvent welding capable of high strength
  • What if the joint leaks?
  • What can I do to help ensure consistent quality for cement?
  • What does NSF stand for?
  • What does IAPMO stand for?
  • Are Weld-KA products certified to both NSF and IAMPO standards?
  • Safety precautions

What is Solvent Cement?

Solvent cements are mixtures of solvents (chemicals) and plastic resins used to weld (join) plastic pipe and fittings. Some cements contain additives and colors depending on application.

How does it Work?

The solvents penetrate (attack) the surfaces of the pipe and fitting, causing them to soften and swell. The swelling of the pipe and fitting continues until the gaps between the two are closed. Resin fills any gaps that may remain open. Solvent are liquid and they evaporate. As the solvents evaporate, the pipe and fitting cure into a single piece of plastic. Solvent cements are not glue and will only join (weld) plastic pipe to each other.

What Plastics can be Solvent Welded?

The most common plastic pipe and fitting that can be solvent welded are:
  • PVC: (Polyvinyl Chloride, vinyl, uPVC)
  • CPVC: (Chlorinated Polyvinyl Chloride, Flowguard)
  • ABS: (Acrylonitrile Butadiene Styrene)

What is Pipe Cleaner

Pipe Cleaner is mixture of solvents used to clean dirt, grease and foreign material on the surface of the pipe. Cleaner should be wiped off (with clean dry cloth) immediately after using. It is very important that the surface of the pipe and the inside of the fitting is very clean and free of all foreign materials.

What is Primer and is it necessary?

Primer is a mixture of solvents used to penetrate (attack) the pipe and fitting prior to the use of solvent cement. Primer starts swelling the pipe and fitting thus ensuring the maximum expansion of the pipe and fitting. Use of primer will result in a stronger joint. Primers should not be wiped off and cement should be applied on top of the primer while it is still wet. We recommend the use of primers when working with pipes and fittings where the diameter of the pipe is in excess of 3 inches.

What are the most commonly used cements?

There are three basic types of Solvent Cements


Used Where?



used on PVC pipe and fittings

drinking and irrigation water


used on CPVC pipe and fittings

hot water application, 140F to 180F


used on ABS pipe and fittings

drainage, irrigation

PVC and CPVC cements can be divided into three (3) categories (grades)




Regular Body

90 to 500 cps

consistency of cooking oil

Medium Body

500 to 1600 cps

consistency of heavy duty engine oil

Heavy Body

1600 cps +

consistency of honey

Regular Bodied

This is an excellent cement for pipe and fittings up to 3” in diameter where gaps between pipe and fitting is snug. Check the dry fit, some resistance should be felt as you insert the pipe in to the fitting. Very cost effective and the most popular. If there is any doubt regarding the snugness of the pipe and fitting use a Medium or Heavy Bodied cement.

Medium Bodied

This cement is designed for pipes and fittings between 3 ” and 6” in diameter. (Always follow the manufacturers’ recommendations). If no resistance is felt as you insert the pipe in to the fitting, we recommend that a second coat of cement should be applied.

Heavy Bodied

This cement is made for pipe and fittings larger than 8” in diameter. If the gaps are large a second coat of cement should also be applied.

How does solvent welding work?

The solvents in the cleaner remove residues that may be on the pipe, leaving a good clean surface. The primer solvents begin the softening process, "etching" or penetrating the pipe. By doing so, the plastic begins to soften and swell. Cement is similar to primer, but contains higher concentrations of active solvents and dissolved resin, similar to the plastics in the pipe and fitting being welded. The pipe and fitting are both coated, connected and bottomed out, and given a 1/4 turn to ensure an even distribution of the cement. The swelling and the tapered shape of the fitting will cause the pipe to attempt to "push-off" of the fitting, so some resistance must be applied until the cement takes a "set". The set usually only takes a minute or two to allow for gentle handling of the joint. The "cure" is the slow increase in strength of the joint. This process involves the evaporation of solvent out of the joint, completing the weld.

How long will it take to set?

Set times are usually under 2 minutes for small pipe sizes. After inserting the pipe into the fitting give a 1/4 turn to distribute cement evenly, you will need to hold the joint firmly to prevent "push-off" caused by the swelling of the pipe and tapered fittings. Once set, it can be released gently and allowed to cure.

How long does the cure take?

The cure time really depends on several things; the temperature, cement body, pipe size and what pressures the system needs to handle when tested. Cure is the diffusion and evaporation of the solvents away from the joint. The material outside the joint may remain flexible for weeks - this is normal. Safe cure times range from 30 min. for 1/2" pipes under low pressure to 8 days for 8" high pressure main lines constructed under freezing weather conditions. Ultimate joint strength develops in most systems after 30 days of cure. The chart below is offered only as a guide for medium and regular cements.

Why are there so many kinds of cement?

There are many types of solvent cement depending on end use, conditions, local codes and contractor requirements. While they all work in a similar manner, special circumstances do exist where benefits can be had using a specialty product, such as All-Temperature in sub freezing conditions, Wet Weld for quick curing strength, or Super Duty cements for large pipe diameters. Our simple 205 Regular PVC and Primer can handle most all PVC install jobs (which are typically small diameter).

How do I choose an applicator for a job?

The applicator dauber, roller, brush or mop should be 1/2 the pipe diameter ( 2” brush/applicator for 4” pipe ). This is to ensure that primer and cement application is done fast enough to avoid dry joints. You cannot use a small can dauber on sizes over 2" and always obtain a good joint - it simply takes too long to coat the pipe and fitting. When you consider the costs of large fittings, the cost of daubers, primer and cement used are insignificant - do it right the first time!

The cement on the outside of the joint is still soft, is this glue still working?

Solvent cement works by fusing or welding two plastics in to a single unit. The actual thickness of the cement layer in a well made joint is very thin. Excess material on the outside of the pipe will take a very long time to cure to the hardness of the pipe, and for that matter, may soften the pipe itself. Excess cement is to be removed when making a joint for that reason.

This cement has become thick/lumpy/dry, what can I do?

NEVER THIN SOLVENT CEMENT. The can may have been left open, and solvents have evaporated away. Given the complex nature of the cement, it cannot be recovered. Attempts to recover the cement by adding primer of cleaner are likely to cause failures in the job being assembled and are NOT worth the risk. The cement must be disposed of properly according to local, state and federal regulations. Keep the cans closed whenever possible - tighten can lid with pliers before any long term storage. Finger-tight is not tight enough to prevent evaporation.

My cement froze, what can I do?

Solvent cement has better resistance to cold than many adhesives, but overnight or longer storage at a job site with conditions that are sub-freezing can cause the cement to thermally jell or substantially thicken - much like "Jell-O" brand gelatin. This behavior tends to effect cements with heavier bodies and higher resin concentrations. Often, product exposed to freezing can be made to return to normal by bringing the jelled product into a warm area for several hours. Recommended storage for these products are between 40 - 90 F. Room temperature is best. Producing joints in sub freezing conditions is possible, but requires additional cure time.

I spilled purple primer, what can I do?

Purple primer is designed to permanently mark PVC pipe for code inspection. Many other household items, such as common plastic floor surfaces, tiles and grout, will also be permanently marked by purple primer, or other cement products. Work carefully!

What problems are reported in the field?

The most often heard of problem is contractors jumping from 1-3" PVC pipe jobs to 8-24" installations with no change in procedures. The techniques, applicators, and prior set-up required in such a case are often overlooked with serious consequences. Using the can dauber on pipes over 4" is hopeless, as the cement begins to dry well before the pipe is coated. Attempting to insert the pipe into the fitting then results in the dried cement coating tearing in places and may make bottoming the fitting impossible - resulting in a dry joint with poor strength, and many leaks. The cement must be fluid to ensure several things; it acts as a lubricant, making insertion easier, it fills gaps in the pipe, preventing leaks and it allows the plastics to weld into a single unit. More than one person is required for larger sizes of pipe, to complete the job Faqin reasonable time and mechanical assistance may be required as well. PVC joints contaminated by debris, sand and materials from the jobsite are also common. Because this material prevents the fitting from being bottomed out, leaks occur. Improper storage of cements can cause failures. Keep the cements from extreme temperatures of hot and cold. Store indoors when possible between 40-90 F. Lids must be kept tight during storage to lessen evaporation. Stir before use, and manufacture a test joint to ensure your ability to produce a quality joint with the jobsite materials. Some may attempt to "salvage" a bad joint by sanding a pipe or fitting for reuse - making a future failure possible. It is poor practice, and may be more expensive to repair later.
A typical failure of poorly installed plastic pipe is caused by poorly prepared pipe - pipe cut at odd angles, and/or not deburred.
The cut made above produces a joint that may sustain initial pressure testing, but leak later on. Under stress, the pipe could break away. In some cases, the burrs left on the pipe will scrape needed cement out of the joint, producing a pathway for a slow leak. The slow leak may over time grow through erosion.

What are the safe precautions for working with these products?

The solvents used in the products are flammable and quickly evaporating. Use precautions to prevent fire or explosion. Keep sources of ignition away from storage and work areas. Vapors can travel and may persist if ventilation is not used. Local exhaust or fans may be required to work in confined spaces, or an approved respirator may be used if solvent fumes exceed limits. Ventilation must be chosen with respect to the flammability of the materials. Wear gloves that are impervious to the solvents in the materials. Eye protection - chemical goggles or face shields should also be used where the risk of eye contact exists. Consult the MSDS and ASTM 402 for more important safety information.

Is solvent welding capable of high strength?

Yes! Lap shear testing, as required by ASTM standards, determines the weld strength over time on flat samples of PVC plastic. Joint strength is +250 lbs/in^2 in two hours and slowly approaches the strength of the plastic in the pipe. The required end PVC strength is 900 PSI and the cure strength will often go much higher. In CPVC testing, under high temperature, the pipe walls often fail before the joints at an incredible 900 psi and 180F.

What if the joint leaks?

Start over. Plastic pipe and fittings with bad joints are non-repairable. You may stop the leak, but it will eventually return. A temporary fix is not worth the risk of a future leak

What can I do to help ensure consistent quality for cement?

Solvent cements have variable shelf life, depending on the following:



Cap tightness

tighter is better

Can manufacturing tolerances

closer is better

Product body

thinner lasts longer

Storage temperature

70F is best

Ingredient purity

purer is best

While some of this is beyond your control, storage conditions and proper rotation of stock, as well as ordering may be. You do your part and we will do ours. Ideally, product should be stored at room temperature, and not outside the range of 40 to 100F. Product should also be rotated to turn over every 6 months. While the typical shelf life of a cement is between 2 to 8 years, to ensure 100% satisfaction, the fresher the product the better.

Examine the Date Codes or box date to determine age of product.
Date Code: 00422

The above date code can be read as follows:
004 (4th day of) 2 (2002) 2 (batch #2)
meaning: 2nd batch of that product made on the 4th of January 2002.

What is NSF stand for?

The Public Health and Safety Company, is an independent, not for profit organization providing a wide range of services around the world. For more than 55 years, NSF has been committed to public health, safety and protection of the environment. While focusing on food, water, indoor air and the environment, NSF develops national standards, provides learning opportunities through its Center for Public Health Education and provides third-party conformity assessment services while representing the interests of all stakeholders. The primary stakeholder groups include industry, the regulatory community and the public at large.
NSF is widely recognized for our scientific and technical expertise in the health and environmental sciences. Its professional staff includes engineers, chemists, toxicologists and environmental health professionals with broad experience both in public and private organizations.
Serving manufacturers operating in more than 80 countries, the NSF Mark is recognized for its value in international trade around the world and is respected by regulatory agencies at the local, state and federal levels.

What does IAPMO stand for?

The International Association of Plumbing and Mechanical Officials, is another third party organization that is well known in the plumbing industry. Since first developing the Uniform Plumbing Code in 1945, IAPMO has been dedicated to the orderly yet aggressive evolution of codes and product standards best able to address the needs of the public and the plumbing/mechanical communities in hundreds of jurisdictions. Products evaluated and listed by the Plumbing and Mechanical Research Committees must meet or exceed the requirements of acceptable, applicable standards and the Uniform Plumbing and Mechanical Codes.
The research committees cause products to be tested in certified independent laboratories all over the United States. If the products, are found acceptable for listing by the Research Committee, they are listed in our Directory of listed plumbing products which lists tens of thousands of products, from fixtures to pipes to septic tanks to back-flow protection devices. The Directory is updated monthly.
In order to safeguard health and safety and to maintain the integrity of IAPMO R&T's Listing Program, its Listing Compliance Department employs a staff of seven inspectors. All independent contractors, these inspectors travel the entire world conducting unannounced inspections of manufacturing plants and warehouses. Compliance with applicable standards and adherence to proper manufacturing methods and processes is verified. Independent laboratory testing of randomly selected samples is conducted. Should products fail to live up to contractual levels of quality, they are ordered withdrawn from the market.


Ensure adequate ventilation to avoid vapor build up which may cause flash fire. Vapor build up may also cause dizziness, headaches or eye watering. If symptoms are experienced use respiratory protection (NOISH/MSHA TC 23 c or equivalent) or leave are and provide more fresh air. Avoid contact with eyes, skin and clothing by use of safety glasses and gloves. Professionals should consult ASTM Standard F 402-93 Safe Handling of Solvent Cements, Primers and Cleaners Used for Joining Thermoplastic Pipe and Fittings. Professional users should also read the Material Safety Data Sheet for the product.

Inhalation:If breathing is difficult vacate to fresh air. If breathing problems persist seek immediate medical attention.

Eyes: Flush eyes thoroughly with water for 15 minutes. Get immediate medical attention.

Internal: If swallowed give 1 or 2 glasses of water immediately, call physician, hospital or poison control immediately. DO NOT INDUCE VOMITING.

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